200-901 DevNet Associate (DEVASC) Question and Answers

RESTCONF and YANG are used for network configuration and management on Cisco IOS XE devices. RESTCONF provides a REST-like interface for accessing YANG-defined data models, allowing engineers to change configurations such as netmasks through programmable interfaces.

References:

Cisco DevNet Associate Study Guide: Network Programmability and Automation (Chapter 6, Section: Using RESTCONF and YANG).

To ensure that changes in a file that already exists in a local repository are included in the next Git commit, the git add command must be executed. This command stages the changes in the specified file(s) so they will be included in the next commit.

A. git update - Incorrect. There is no git update command. B. git merge - Incorrect. This command is used to merge branches, not to stage changes. C. git add - Correct. This command stages changes in the working directory to be included in the next commit. D. git rebase - Incorrect. This command is used to reapply commits on top of another base tip.

References:

Git Basics - Recording Changes to the Repository

The HTTP client error response code accompanied by a Retry-After header typically indicates that the client has sent too many requests in a given amount of time, leading to rate limiting by the server. This is often indicated by a 429 Too Many Requests status code. The Retry-After header informs the client how long it should wait before making another request.

References:

Cisco DevNet Associate Study Guide: REST API Error Handling (Chapter 7, Section: Understanding HTTP Status Codes).

The first three pairs of digits in a MAC address, also known as the Organizationally Unique Identifier (OUI), identify the vendor or manufacturer of the network card or adapter. This part of the MAC address is assigned by the IEEE to the manufacturers, ensuring that each MAC address is unique.

Organizing code into modules allows for code reuse, which simplifies maintenance and improves efficiency. Modules encapsulate specific functionality, making it easier to manage and update. This approach reduces redundancy, as common functions can be written once and reused across multiple programs, leading to more manageable and maintainable codebases.

References:

Cisco DevNet Associate Study Guide: Software Development and Design (Chapter 3, Section: Modular Programming and Code Reuse).

The exhibit shows a unified diff output, which indicates changes made to files in a version control system (e.g., git). The files being edited are indicated by the diff --git lines.

Identifying Files: The diff output shows changes to two files:

ciscoaxl/axl.py: Indicated by the line diff --git a/ciscoaxl/axl.py b/ciscoaxl/axl.py.

setup.py: Indicated by the line diff --git a/setup.py b/setup.py.

Unified Diff Format: The format includes the file paths, lines added (+), and lines removed (-).

Options B and D are the correct answers as they correspond to the files setup.py and ciscoaxl/axl.py.

A routing table on a network device serves as a map for determining the best path to route packets to their destinations. It lists all the routes to particular destinations, including both the next-hop addresses and the associated metrics. The routing table also includes static entries (manually configured routes) and dynamic entries (routes learned through routing protocols).

References:

Cisco DevNet Associate Study Guide: Understanding Routing Tables (Chapter 4, Section: Routing and Switching Fundamentals).

In the Ansible playbook, the last task uses the apt module with state: absent and purge: yes for the webexbot package. This configuration ensures that the package is uninstalled and all associated configuration files are removed. This is different from a simple uninstall, which would leave configuration files behind.

References:

Cisco DevNet Associate Study Guide: Automation with Ansible (Chapter 7, Section: Ansible Playbook Examples and Syntax).

A developer is creating a script to interact with a REST API service that requires basic authentication. The correct combination of payload and headers using Basic Authentication with the provided Base64 encoded credentials is:

A. This option does not use headers correctly. B. Option B - Correct. This option correctly places the 'Authorization' header in the headers dictionary with 'Basic' authentication. C. This option uses 'Bearer' instead of 'Basic' for the 'Authorization' header. D. This option uses 'Bearer' instead of 'Basic' for the 'Authorization' header.

References:

HTTP Authentication

Base64 Encoding

The NETCONF RPC message shown in the exhibit requests the running configuration of the device filtered to show only interface names.

A. The running-config of the device is returned - Correct. The RPC message with the operation retrieves the running configuration filtered to include only the interface names. B. The name of each interface is reset to a default name - Incorrect. The RPC message is a read operation, not a configuration change. C. All the YANG capabilities supported by the device are returned - Incorrect. The RPC message specifically targets the running configuration, not the YANG capabilities. D. A list of interface names is returned - Incorrect. While the filter is for interface names, the context is that the running configuration containing these interface names is returned.

References:

NETCONF Protocol Operations

YANG Data Modeling Language

Answer: A

Top of Form

Bottom of Form

To create a running container based on a tagged Docker image with the container port 8080 bound to port 80 on the host, you use the docker run command with the -p flag.

A. docker build -p 8080:80 alpine

- Incorrect. docker build is used to build an image, not run a container. B. docker exec -p 8080:80 alpine

- Incorrect. docker exec is used to run a command in a running container. C. docker start -p 8080:80 alpine

- Incorrect. docker start starts a stopped container but does not create one. D. docker run -p 8080:80 alpine

- Correct. This command runs a new container from the image and maps the ports.

References:

Docker Run Command

The provided Ansible playbook automates the process of ensuring the nginx server is installed while removing apache2, and then updates all the packages to their latest versions.

Task 1: Ensures that apache2 is uninstalled (state: absent).

Task 2: Ensures that nginx is installed (state: present).

Task 3: Updates all packages to their latest versions (state: latest).

Option C accurately describes the process automated by the Ansible playbook.

In the provided Python function enable_function, the parameters are if_name, if_status, and if_type, which correspond to the interface name, status (enabled/disabled), and interface type respectively.

Function Parameters: The function enable_function is designed to take three parameters: the interface name (if_name), the status (if_status), and the type (if_type).

Correct Order and Values: To enable the interface named "Loopback1", you need to pass the correct values in the order they are defined in the function.

Option A correctly calls the function with the interface name "Loopback1", the status true (enabled), and the interface type 'iana-if-type:softwareLoopback'.

The Cisco DevNet API documentation is the primary resource for understanding the meanings of response codes received from REST API calls. It provides comprehensive details about the API endpoints, response codes, and their interpretations, which helps developers troubleshoot and understand the responses they receive.

The EXPOSE instruction in a Dockerfile informs Docker that the container listens on the specified network ports at runtime. This does not publish the ports to the host machine, but it allows them to be connected to from other containers.

A. Local port 8080 of the container that launched with this docker image is accessible from co-hosted containers and external clients - Incorrect. The EXPOSE instruction does not make the port accessible to external clients. B. Local port 8080 is not reachable at all because no IP address is specified along with the EXPOSE command of the Dockerfile - Incorrect. The EXPOSE instruction does not require an IP address. C. Local port 8080 is accessible from other containers running on the same docker host as the container that launched with this docker image - Correct. The EXPOSE instruction makes the port available for inter-container communication. D. Local port 8080 of the container that launched with this docker image is accessible to external clients - Incorrect. The EXPOSE instruction does not publish the port to external clients.

References:

Dockerfile reference - EXPOSE

The HTTP call to create a room named "cisco" through the Webex API is returning a 400 Bad Request error because the body parameter is incorrect. The correct body parameter to create a room is "name" instead of "team".

A. Replace the team body parameter with the name body parameter - Correct. The correct parameter for creating a room is "name". B. Replace cisco with a valid name for a team - Incorrect. The issue is with the parameter name, not the value. C. Change the token in the header with the authorization token - Incorrect. The token appears to be correct since it is a 400 error and not a 401 Unauthorized error. D. Change the HTTP method of the call to PUT - Incorrect. The correct HTTP method for creating a room is POST.

References:

Cisco Webex API Documentation - Create a Room

The 401 Unauthorized response indicates that the API call lacks proper authentication. To authenticate a request using a Bearer token, the correct headers must be included. The "Authorization: Bearer " header is the correct format for including a Bearer token in an API request. Additionally, specifying the correct content type can also be important, but in this case, the critical headers are related to authorization.

References:

Cisco DevNet Associate Study Guide: API Authentication (Chapter 7, Section: Authentication Methods for REST APIs).

In test-driven development (TDD), the "green bar" refers to the visual indication that all tests have passed, typically seen in a testing framework. Two of the patterns that developers use to reach the green bar in TDD are "triangulate" and "fake it."

A. another test - This is not a green bar pattern; it's a step in the TDD cycle but not a pattern for passing tests. B. break - This is not a TDD pattern. C. triangulate - Correct. Triangulation involves adding another test to force the implementation to be more generic and robust. D. starter test - This is not a TDD pattern. E. fake it - Correct. Faking it means to return a simple, hard-coded value to make the test pass.

References:

Test-Driven Development (TDD) Patterns

Growing Object-Oriented Software, Guided by Tests

The script returns a 401 Unauthorized response, indicating that the request lacks proper authentication. To resolve this, you must include an Authorization header in the HTTP GET request. The value of this header should be the Base64 encoded string of the username and password in the format username:password. This is necessary to authenticate the request and receive a 200 OK response.

References:

Cisco DevNet Associate Study Guide: REST API Authentication Methods (Chapter 7, Section: HTTP Basic Authentication).

To integrate changes from an existing branch named 'feat00304' into a single commit with the current working primary branch 'prodapp411926287', the git merge --squash command must be used. This command squashes all commits from the feature branch into a single commit before merging.

A. git rebase --merge feat00304 - Incorrect. This command does not perform a squash merge. B. git merge --squash feat00304 - Correct. This command squashes all commits from 'feat00304' into a single commit and then merges it. C. git push --rebase feat00304 - Incorrect. This command is used for pushing changes and rebasing, not for squashing commits. D. git checkout --squash feat00304 - Incorrect. This command is invalid.

References:

Git Merge Squash

The bash script shown in the exhibit automates the process of downloading, extracting, compiling, installing, and configuring the Cisco DevNet application. It also enables and starts the application automatically.

Download and Extract: The script uses curl to download a tar.gz file and then extracts it using tar -zxf.

Compilation and Installation: The ./configure && make && make install commands compile and install the application.

Enabling and Starting the Service: The systemctl enable devnet and systemctl start devnet commands ensure the application starts automatically on system boot and starts it immediately.

Option B correctly describes the workflow as it includes compilation, installation, configuration, and automatic startup of the application.

Refactoring is done during test-driven development (TDD) to improve the maintainability and readability of the code. After writing tests and ensuring that the code passes those tests, developers refactor to clean up the code, making it more efficient and easier to understand without changing its functionality.

A. to enable larger objects and longer methods - Incorrect. Refactoring aims to simplify and streamline code, not make it larger or more complex. B. to improve maintainability and readability - Correct. Refactoring makes the code easier to maintain and understand. C. to ensure that the previous uses of the objects are explained - Incorrect. This is not the purpose of refactoring. D. to ensure the duplication of essential code - Incorrect. Refactoring seeks to reduce code duplication, not ensure it.

References:

Test-Driven Development by Example

Common data formats like JSON and YAML are typically parsed into a Python dictionary. This is because dictionaries in Python provide a way to store data in key-value pairs, which is similar to the structure of these data formats.

A. sequence - Incorrect. This is a general term that includes lists, tuples, etc. B. set - Incorrect. A set is an unordered collection of unique elements, which is not suitable for key-value pairs. C. dictionary - Correct. Dictionaries are used to store data in key-value pairs. D. list - Incorrect. Lists are ordered collections of items, which are not suitable for key-value pairs.

References:

Python Data Structures

JSON and YAML Parsing

The Python script in the exhibit interacts with Cisco DNA Center APIs to query devices and execute commands. It collects the results of specific show commands from the devices.

Device Query: The script first queries for devices with the platformId of 'C9500-40X'.

Command Execution: It sends commands (show version, show ip int brief) to these devices.

Result Gathering: The script retrieves and processes the results of the executed commands.

Option A accurately describes the process automated by the script, which is to gather the results of the show version and show ip int brief commands.

Synchronous API requests and asynchronous API requests differ primarily in how and when the client receives a response from the server.

Synchronous API Request: In a synchronous API call, the client sends a request to the server and waits for a response. The client is blocked during this time, meaning it cannot perform other tasks until the server responds. The key characteristic is that the client is able to access the results immediately after the request is processed. This is suitable for operations that need an immediate response and where the processing time is relatively short.

Asynchronous API Request: In an asynchronous API call, the client sends a request and continues its process without waiting for the server to respond. The server processes the request and sends the response back to the client at a later time. The client might receive a task ID (option A), subscribe to a webhook (option B), or poll for status (option D) to check when the operation is complete.

The exhibit illustrates a Continuous Integration/Continuous Deployment (CI/CD) pipeline. This method involves continuous integration of code from multiple developers, automated testing, and continuous delivery/deployment to production. It ensures that code changes are automatically built, tested, and deployed, promoting efficient and reliable software development practices.

To ensure the Python code runs successfully, the environment variable WEBEX_TEAMS_ACCESS_TOKEN must be set. This can be done using the export command in a Bash script.

A. define WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Incorrect. define is not a valid Bash command for setting environment variables. B. export WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Correct. This command correctly sets the environment variable for the current session. C. set WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Incorrect. set is not used in this context for setting environment variables in Bash. D. WEBEX_TEAMS_ACCESS_TOKEN=your_access_token_here - Incorrect. This command sets the variable but does not export it to be available to child processes.

References:

Setting Environment Variables in Bash

The provided documentation outlines how to use Basic HTTP Authentication with the Cisco AMP API. The correct method involves encoding the client ID and API key in base64 format and then including them in the authorization header. However, in the given scripts, the use of the requests library’s auth parameter directly with the client ID and API key is also a valid method.

Option A correctly uses the requests library to make an API call with the client ID and API key. This method is supported and valid as per the documentation.

python

Copy code

import requests

amp_client_id = 'alb2c3d4e5f6g7h8i9j0'

amp_login_password = 'l0g1n_p@ssw0rd'

url = 'https://api.amp.cisco.com/v1/version '

request = requests.get(url,

auth=(amp_client_id, amp_login_password))

print(request.json())

Client ID and API Key: amp_client_id and amp_login_password are set with the values provided.

URL: The URL for the AMP API endpoint is correctly set.

GET Request: The requests.get method is used with the auth parameter that takes a tuple of the client ID and API key.

Response: The response is printed in JSON format.

Option B:

Does not use the auth parameter or a header for Basic Authentication, thus it will fail.

Option C:

Uses a single amp_auth_token which does not follow the provided documentation method.

Option D:

Incorrectly uses the auth parameter with a concatenated client ID and API key without specifying Basic Authentication in the header.

References:

Cisco AMP for Endpoints API Documentation

Requests: Authentication

The Bash script performs the following steps within the loop:

Reads each line from sites.txt.

Copies template.conf to a new file in the /etc/nginx/sites-available directory for each site.

Creates a symbolic link to the new file in the /etc/nginx/sites-enabled directory.

Changes the ownership of the new files to www-data.

This process creates a configuration file for each site, creates a link to enable the site, and ensures the correct permissions.

When selecting the "best route" for a network device to reach its destination, the considerations include:

Metrics: These are values used by routing protocols to determine the best path to a destination. Metrics can include factors like hop count, bandwidth, delay, load, and reliability.

Administrative Distance: This is a value used to rate the trustworthiness of the source of the routing information. Lower values indicate more trusted routes.

SSH (Secure Shell) is a protocol that provides a secure channel over an unsecured network by using encryption. It operates over TCP port 22 and is commonly used for remote login and command execution on network devices and servers. SSH ensures secure communication between the client and server by encrypting the session.

References:

Cisco DevNet Associate Study Guide: Understanding Network Protocols (Chapter 2, Section: Common Network Protocols and Ports).

A reverse proxy can be used to route external requests to different applications on the same host machine using a single public IP address and port. It forwards the requests to the appropriate backend servers based on the request URL or other routing rules.

Single Entry Point: A reverse proxy serves as a single entry point to multiple applications, making it ideal for managing traffic to multiple services hosted on the same machine.

Routing Requests: It can route requests to different internal ports based on the requested URL or other criteria.

Option A is the correct choice as a reverse proxy handles external access to multiple applications on the same host.

The error in the Python code is due to the requests library not being defined, which typically means it hasn't been installed. To resolve this issue, the requests library needs to be installed using the pip install requests command. This will add the necessary module to the Python environment, allowing the code to execute correctly.

To determine the correct JSON snippet for configuring a new interface according to the YANG model, we need to carefully examine both the YANG model definitions and the provided JSON snippets. Here’s a step-by-step explanation:

YANG Model Analysis:

The ietf-interfaces YANG module defines a container interfaces with a list interface.

Each interface has the following important leaves: name, enabled, and description.

The ietf-ip YANG module augments the interface list with a container ipv4, which includes a list address. Each address has the ip and netmask leaves.

Key Elements in JSON:

To configure an interface, the JSON must include the name of the interface, its enabled status, and the IP address configuration.

The structure should reflect the hierarchy defined by the YANG models.

Options Analysis:

Option A:

json

Copy code

"ietf-interfaces:interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip:ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

This option correctly follows the hierarchy specified in the YANG model. The interface includes name and enabled leaves and augments with ietf-ip:ipv4 which includes the address list with ip and netmask.

Option B:

"ietf-interfaces": {

"interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip": {

"ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

}

}

This option incorrectly nests interface directly under ietf-interfaces, which does not match the YANG model’s structure.

Option C:

"interface": {

"name": "Loopback100",

"enabled": true,

"ipv4": {

"address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

}

This option misses the namespace prefixes ietf-interfaces and ietf-ip required by the YANG model.

Option D:

"ietf-interfaces:interface": {

"name": "Loopback100",

"enabled": true,

"ietf-ip:ipv4:address": [

{

"ip": "10.255.254.1",

"netmask": "255.255.255.0"

}

]

}

This option incorrectly uses ietf-ip:ipv4:address directly, which does not align with the proper hierarchy where address should be nested inside ipv4.

Correct Explanation:

Option A correctly adheres to the YANG model hierarchy and namespace specifications.

It properly nests address within ipv4, which is itself nested within ietf-ip augmentation to interface.

This structure is consistent with how the YANG models define the relationships between the elements.

References:

Understanding of YANG models and their use: Cisco DevNet YANG Introduction

YANG Data Models in NETCONF: RFC 6020

Telnet is a protocol used for accessing remote computers over a TCP/IP network, and it runs over TCP port 23.

Telnet Protocol: Telnet allows remote command-line interface access to network devices and servers.

Port 23: The standard port for Telnet is TCP port 23.

Option D is correct as Telnet operates over TCP port 23.

The docker build command is used to build an image from a Dockerfile. The -t option tags the image with a specified name and tag.

Tagging: The docker tag command associates an image ID with a repository and tag.

Building with Tag: The correct command to build the Docker image and tag it as local/app:0.4 is docker build -t local/app:0.4.

Option D is the correct command to build and tag the image.

To create and switch to a new branch called "my-bug-fix" in Git, you use the git checkout -b command. This command creates the branch and switches to it in one step.

A. git checkout -b my-bug-fix - Correct. This command creates a new branch and switches to it. B. git branch -b my-bug-fix - Incorrect. The -b option is not valid with git branch. C. git branch my-bug-fix - This creates a new branch but does not switch to it. D. git checkout my-bug-fix - This switches to an existing branch but does not create a new one.

References:

Git Branching - Creating a Branch

A model-driven approach for infrastructure automation offers several benefits. One of the primary advantages is that it provides a small learning curve and helps system administrators with limited coding experience. By using high-level models and declarative languages, administrators can define the desired state of the infrastructure without needing to write complex scripts.

Declarative Language: Model-driven approaches use declarative languages that allow users to specify what the desired state should be, rather than how to achieve that state. This abstracts the complexity of the underlying automation processes.

References: Cisco DevNet Associate Certification Guide, Chapter on Infrastructure as Code and Model-Driven Programmability.

To restrict access to the management interface of devices using SSH and HTTPS, the correct ports need to be included in the ACLs.

Port 22: Used by SSH (Secure Shell) for secure remote login and command execution.

Port 443: Used by HTTPS (Hypertext Transfer Protocol Secure) for secure web traffic.

Options A and D are correct as they are the standard ports for SSH and HTTPS.

The task is to determine which command correctly outputs the page_id value from the JSON payload shown in the Python 3.7 script. Let’s analyze the options and the payload structure to verify the correct answer.

JSON Payload Analysis:

The JSON payload provided in the exhibit shows that items is a key in the top-level dictionary.

The value of items is a list of dictionaries, and each dictionary contains various keys, including page_id.

Code Analysis:

The JSON data returned by the get_json function is assigned to the variable items.

The goal is to access the page_id key within the first dictionary of the list associated with the items key.

Options Analysis:

Option A: print(items['items']['page_id'])

This will not work because items['items'] is a list, not a dictionary. Attempting to access ['page_id'] directly from a list will result in a TypeError.

Option B: print(items.get('items').get('page_id'))

This will also not work for the same reason as Option A. items.get('items') returns a list, and calling .get('page_id') on a list is invalid.

Option C: print(items.get('items')[0].get('page_id'))

This is correct. items.get('items') returns the list, [0] accesses the first element of the list (which is a dictionary), and .get('page_id') retrieves the value of the page_id key from that dictionary.

Option D: print(items['items']['page_id'].keys())

This will fail because items['items'] is a list and does not have a keys() method.

Correct Explanation:

The JSON structure contains a list under the key items.

To access page_id, we first need to get the first dictionary in this list ([0]).

We then access the page_id key in this dictionary.

Example:

print(items.get('items')[0].get('page_id'))

This code correctly navigates through the structure and retrieves the value associated with page_id.

References:

Python Documentation on Dictionaries: Python Docs

JSON Data Handling in Python: Python JSON

In a CI/CD (Continuous Integration/Continuous Deployment) pipeline, it is a common procedural component that every test must pass for the pipeline to continue its execution. This ensures that only code that meets the quality standards and passes all tests is deployed, thereby reducing the risk of introducing bugs or issues into the production environment.

Simple Network Management Protocol (SNMP) is widely used for network management and monitoring. It allows administrators to monitor and manage network devices such as routers, switches, and servers by collecting information on device performance, status, and errors.

SNMP: Provides a framework for exchanging management information between network devices. It helps in monitoring network performance, detecting faults, and configuring devices remotely.

Other Protocols:

DHCP: Used for dynamic IP address assignment.

DNS: Resolves domain names to IP addresses.

NTP: Synchronizes time across network devices.

References:

Cisco DevNet Associate Certification Guide

Cisco SNMP Overview

Version control systems (VCS) are essential for managing changes to code and files in a project. They track all modifications, enabling multiple users to work collaboratively while maintaining a history of changes.

Tracking Changes: VCS keeps a detailed history of changes made to files, including who made the change and when.

Collaboration: Multiple users can work on the same project simultaneously without overwriting each other's work.

Reverting Changes: It allows reverting to previous versions if a mistake is made.

Option B is correct as it highlights the primary benefit of version control—keeping track of all changes to the files.

To protect secrets such as API URLs, shared keys, and other application configurations, it is best practice to: C. Ensure they never appear in plaintext at rest or in transit. Encrypt sensitive data both when it is stored (at rest) and when it is transmitted over the network (in transit). This prevents unauthorized access and exposure. E. Always store secrets in a secure vault. Use dedicated secret management tools like HashiCorp Vault, AWS Secrets Manager, or Azure Key Vault to store and manage sensitive information securely. These tools provide mechanisms for access control, audit logging, and automatic rotation of secrets.

References:

Securing Secrets

HashiCorp Vault

AWS Secrets Manager

Cisco Intersight is a platform designed to manage data center infrastructure through third-party tools and system integrations. It provides a unified management platform that integrates with Cisco UCS, HyperFlex, and other data center components, allowing for comprehensive infrastructure management, automation, and orchestration.

References:

Cisco Intersight - Overview

Cisco DevNet Associate Certification Guide

The Python script provided is designed to make a POST request to a REST API to create a new task in a to-do list application. Here's a step-by-step explanation of the script:

Import the requests library to handle HTTP requests.

Define the task dictionary with summary and description.

Use the requests.post method to send a POST request to the specified URL, passing the task data as JSON and setting the appropriate Content-Type header.

Check if the response status code is not 201 (which indicates successful creation). If it's not, raise an ApiError with the status code.

Print the created task's ID from the JSON response.

The provided code options are:

requests: the library used for making HTTP requests.

status_code: used to check the HTTP response status.

Content-Type: a header specifying the media type of the resource.

raise: used to raise an exception if the status code is not as expected.

return is not used in this context.

References:

Cisco DevNet Associate Certification Guide

Python Requests Library Documentation

YAML and JSON are both data serialization formats often used in configuration files. One of the key differences is that YAML supports comments, whereas JSON does not.

Comments: YAML allows comments, which makes it easier to add explanatory notes within the configuration files.

Data Representation: Both formats are used to represent data structures, but YAML is often considered more human-readable.

Option B is correct as it highlights the difference that YAML supports comments while JSON does not.

The principle that best describes the DevOps practice outlined in the question is "end-to-end responsibility". In DevOps, teams are responsible for the entire lifecycle of the application, including development, deployment, continuous integration/continuous delivery (CI/CD), monitoring, and performance improvements. This holistic approach ensures that the same team manages all aspects of the application's lifecycle, leading to better collaboration, faster deployment cycles, and improved overall quality and reliability of the software.

References:

Cisco DevNet Associate Certification Guide

DevOps Handbook: How to Create World-Class Agility, Reliability, & Security in Technology Organizations

Virtual machines (VMs) provide the flexibility and capabilities required to meet the described requirements. VMs can easily migrate between data centers, save and restore their state, and support various operating systems and GUIs.

Migration: VMs can be moved from one physical server or data center to another, providing high flexibility in resource management.

State Saving: VMs support saving the operational state (snapshots), allowing quick recovery or migration.

Support for GUIs: VMs can run different operating systems, including those with graphical user interfaces (GUIs) like Windows and Linux.

Hardware Utilization: VMs enable better utilization of hardware resources by running multiple VMs on a single physical host.

References:

Virtual Machines Overview: VMware VMs

REST APIs are designed around resources that are identified by URLs. Operations are performed on these resources using standard HTTP methods like GET, POST, PUT, and DELETE. In contrast, RPC (Remote Procedure Call) APIs are designed around actions or operations, where the focus is on invoking methods or functions rather than manipulating resources.

The Python script shown in the exhibit is designed to interact with Cisco DNA Center APIs. Here's a step-by-step breakdown of what the script does:

It imports necessary libraries and sets the BASE_URL, AUTH_URL, and TOKEN for authentication.

It defines the headers to include the authentication token and content type.

It constructs URLs for fetching the device count, all devices, and devices by ID.

The devices_func function makes a GET request to fetch the total count of devices.

The devices_test function fetches a list of network devices based on query parameters.

The devices_info function retrieves detailed information about a specific device using its ID.

The script then prints the total count of devices, all devices, and filtered device information based on the hostname and platform ID.

In the final step, after executing the script, it fetches devices with the hostname "CSR1Kv-01.devnet.local" and then filters the list by platform ID "C9500-40X". This results in displaying the filtered information about the device that matches both the hostname and platform ID criteria.

References:

Cisco DevNet Associate Certification Guide

Cisco DNA Center API Documentation

To enable keepalive for the FastEthernet 2/0 interface using YANG data models and NETCONF in Python, the following steps are required:

Create an Interface Object:

interface = model.Native.Interface.FastEthernet()

This line creates an instance of the FastEthernet interface from the YANG model.

Set the Interface Name:

interface.name = '2/0'

This line sets the name of the interface to 2/0.

Enable Keepalive:

interface.FastEthernet.keepalive_settings.keepalive = True

This line enables the keepalive setting on the FastEthernet interface.

Read the Current Configuration:

interface_data = crud.read(provider, interface)

This line reads the current configuration of the interface from the device.

Update the Configuration:

crud.update(provider, interface)

This line updates the device configuration with the new settings, enabling keepalive on the specified interface.

References:

Cisco YANG Data Models: Cisco YANG Models

YANG Development Kit (YDK): YDK Documentation

To minimize the security risk, storing the username and password in a vault is the best practice. A vault, such as HashiCorp Vault or AWS Secrets Manager, securely stores and manages sensitive information, providing encryption and access control. This approach ensures that credentials are not hard-coded or stored in insecure locations, reducing the risk of exposure.

from ucsmsdk.ucshandle import UcsHandle

connection = UcsHandle("10.10.20.113", "ucspe", "ucspe")

connection.login()

orgs = []

ucsm_orgs = connection.query_classid("orgOrg")

for org in ucsm_orgs:

temp_org = {"name": org.name, "dn": org.dn, "rn": org.rn}

orgs.append(temp_org)

print(orgs)

Understanding the UCSHandle Class:

Purpose: The UcsHandle class is used to interface with the UCS Manager.

Parameters: It requires parameters like IP address, username, password, port, secure, and proxy.

Python Script Explanation:

Importing UcsHandle: The first step is to import the UcsHandle class from the ucsmsdk.ucshandle module.

Creating a Connection: An instance of UcsHandle is created with the UCS Manager's IP address, username, and password.

Login: The login() method is called on the UcsHandle instance to establish a session with the UCS Manager.

Querying Organizations: The query_classid() method is used to retrieve objects of a specific class, in this case, "orgOrg" which represents organizations.

Looping through Results: The script iterates over the retrieved organizations, extracting their name, distinguished name (dn), and relative name (rn), and appending this information to the orgs list.

Printing Results: Finally, the orgs list is printed, which contains the details of all the organizations.

References:

Cisco DevNet Associate Certification Guide, Sections on UCS Manager API and Python SDK

UCS Python SDK Documentation

When a mobile phone using 4G fails to access the application, it is likely because the application is hosted on-premises and requires VPN connectivity to access it. On-premises applications often have network restrictions for security reasons, and access from external networks (such as 4G) typically requires a secure VPN connection to ensure data security and compliance with access policies.

The YANG model provided in the exhibit defines the structure for interface information, including fields for name, admin-status, if-index, and statistics. The correct XML snippet must match this structure and use the appropriate namespaces and field names as defined in the YANG model.

Namespace: The XML must include the namespace urn:ietf:params:xml:ns:yang:ietf-interfaces and the prefix if.

Interface Information: The XML must include elements for name, admin-status, if-index, and statistics as defined in the YANG model.

Field Names and Values: The field names must match the YANG model (admin-status, if-index, in-octets, in-unicast-pkts).

Option D is the correct XML snippet because it accurately conforms to the YANG model. It includes the required elements and correctly uses the namespace and field names:

GigabitEthernet1

1

1

408164820

728061

The HTTP 401 Unauthorized error indicates that the request lacks proper authentication credentials. However, in this case, the credentials are provided, so the issue likely stems from a missing or incorrect header. The Content-Type header is necessary for many REST APIs to specify the format of the request body. Adding the Content-Type: application/yang-data+json header ensures that the server correctly interprets the request as JSON formatted data according to the YANG data model.

References:

Cisco DevNet Associate Certification Guide

Cisco IOS XE RESTCONF API Documentation

To download and execute an Apache web server container in Docker, you need to perform two steps: pulling the image and running the container with the appropriate port bindings.

docker pull httpd - This command downloads the Apache HTTP server image from the Docker repository. "httpd" is the official name for the Apache HTTP server image on Docker Hub.

docker run -p 8080:80 httpd - This command runs a new container from the "httpd" image, mapping port 8080 on the host to port 80 in the container. This allows you to access the web server running in the container via port 8080 on your host machine.

References:

Docker Documentation - docker pull

Docker Documentation - docker run

Cisco DevNet Associate Certification Guide

To copy a file from one directory to another and rename it in the process, the cp (copy) command in Linux can be used with the appropriate source and destination paths:

Command Breakdown:

cp: The copy command.

./TEST/config.txt: The source file path.

./PROD/current.txt: The destination file path with the new name.

Thus, the correct command to achieve this task is: cp ./TEST/config.txt ./PROD/current.txt

References:

Linux cp Command Manual

Cisco DevNet Associate Certification Guide

The exhibit shows that the credentials are base64 encoded and included in the source code. Base64 encoding is not a secure method of protecting credentials as it can be easily decoded. Therefore, an attacker who gains access to the source code can decode the credentials and gain unauthorized access to the account. Proper security practices should involve storing credentials securely, such as using environment variables or secure vaults, and not hardcoding them in the source code.

References:

OWASP - Storing Passwords Securely

Cisco DevNet Associate Certification Guide

When configuring a Cisco IOS XE networking device using RESTCONF, the default data encoding method is application/yang-data+json. This MIME type indicates that the data is encoded in JSON format and structured according to YANG data models. YANG (Yet Another Next Generation) is a data modeling language used to model configuration and state data manipulated by the NETCONF protocol, which RESTCONF leverages.

References:

Cisco DevNet Documentation - RESTCONF

Cisco DevNet Associate Certification Guide

Infrastructure as Code (IaC) applies software development practices to infrastructure management. This approach uses code to provision and manage IT infrastructure, enabling version control, automated testing, and continuous delivery.

Automated Provisioning: IaC scripts automate the setup and configuration of infrastructure resources.

Consistency: By defining infrastructure in code, environments can be consistently reproduced across different stages (development, testing, production).

Development Practices: IaC allows infrastructure to be managed with the same tools and processes as application code, including version control and automated testing.

References:

Infrastructure as Code Overview: IaC Introduction

An Ethernet switch operates at the Data Link layer (Layer 2) of the OSI model. Its primary function is to forward frames between devices based on their MAC (Media Access Control) addresses. When a frame arrives at the switch, the switch reads the destination MAC address and forwards the frame to the appropriate port that connects to the device with that MAC address.

MAC Address Table: Switches maintain a MAC address table that maps each MAC address to a specific port. This table is built dynamically as the switch learns the MAC addresses of devices connected to its ports.

Frame Switching: By using the MAC address table, the switch can efficiently switch frames only to the destination port, which reduces unnecessary traffic on other ports and improves network performance.

References:

Cisco DevNet Associate Certification Guide

Cisco Ethernet Switch Operation

To obtain a token from the Cisco DNA Center API using HTTP Basic Authentication, the requests library in Python is used. The missing line of code in the snippet should set up HTTP Basic Authentication as follows:

auth=HTTPBasicAuth(user,password)

HTTPBasicAuth: This is a class from the requests.auth module that handles HTTP Basic Authentication.

user, password: These are the credentials required for authentication.

The correct line of code that completes the script to obtain a token from Cisco DNA Center API is:

python

Copy code

auth=HTTPBasicAuth(user,password)

References:

Requests Library Documentation - HTTPBasicAuth

Cisco DevNet Associate Certification Guide

When conflicts occur during a merge, the git merge --abort command can be used to stop the merge process and revert the repository to its state before the merge began.

Merge Conflicts: Occur when changes from different branches cannot be automatically reconciled.

Abort Merge: git merge --abort undoes the merge process and restores the pre-merge state of the repository.

Option D is correct as it correctly uses the git merge --abort command to revert to the pre-merge state.

Cross-Site Request Forgery (CSRF) is a type of attack that forges a malicious HTTP request and sends it from a user's browser to a different site where the user is authenticated. The attacker tricks the user into executing unwanted actions on a web application in which the user is currently authenticated. This can lead to unauthorized actions being performed on the user's behalf.

References:

Cisco DevNet Associate Certification Guide

OWASP CSRF Prevention Cheat Sheet

Cisco Webex offers a range of collaboration capabilities, including real-time messaging, video conferencing, and integration with various productivity tools. Specifically, Webex allows users to:

Get Space History: Users can retrieve historical messages and files shared within a space, ensuring they have access to all past communications and documents.

Real-Time Notifications: Webex provides notifications when new messages are posted in spaces, allowing users to stay updated with ongoing conversations and respond promptly.

These features enhance the collaborative experience by ensuring users can keep track of conversations and receive timely updates.

References:

Cisco Webex Features

The subnet mask is used to determine the network and host portions of an IP address. It helps in defining the size of the subnet and the range of IP addresses within that subnet.

Subnet Portion: The subnet mask identifies which part of the IP address refers to the network (subnet) portion.

Host Portion: The remaining part of the IP address after applying the subnet mask identifies the specific host within the subnet.

Options A and D are correct as they capture the details about the subnet and host portions of an IP address.

RPC (Remote Procedure Call) APIs and REST (Representational State Transfer) APIs have different approaches to communication and authentication.

RPC APIs: Authentication can be more complex and is often embedded within the service calls themselves, sometimes requiring specific provisions for the caller and the service.

REST APIs: Authentication typically relies on standardized methods such as HTTP headers, including Basic Auth, OAuth tokens, or API keys, making it more straightforward and standardized across different services.

References:

Cisco DevNet Documentation - APIs

Cisco DevNet Associate Certification Guide

import requests

data = {

"id": 11,

"summary": "Request summary"

}

response = requests.post('https://todolist.example.com/tasks/ ', json=data)

if response.status_code != 201:

raise ApiError('POST /tasks/ {}'.format(response.status_code))

for item in response.json():

print('{} {}'.format(item['id'], item['summary']))

Importing the Requests Library:

The requests library is used to make HTTP requests in Python. It is a popular third-party library that simplifies interactions with web APIs.

Creating the Data Payload:

The data dictionary contains the information to be sent in the body of the POST request. It includes an id and a summary.

Making the POST Request:

The requests.post method is used to send a POST request to the specified URL (https://todolist.example.com/tasks/). The json=data parameter automatically converts the data dictionary to a JSON-formatted string and sets the appropriate headers.

Checking the Response Status Code:

The script checks if the status_code of the response is not equal to 201. A status code of 201 indicates that the request was successful and a resource was created.

If the status code is not 201, an ApiError is raised with a message that includes the status code.

Processing the JSON Response:

The response.json() method is used to parse the JSON response into a Python dictionary.

The script iterates over the items in the JSON response and prints the id and summary of each item.

References:

Cisco DevNet Associate Certification Guide, Sections on interacting with REST APIs using Python

Official documentation for the Requests library: Requests: HTTP for Humans

In the given Dockerfile, the WORKDIR /app command sets the working directory for any subsequent commands to /app. This means that any commands following this line will be executed within the /app directory inside the Docker container. The COPY . . command copies the contents of the current directory on the host machine to the /app directory in the container. Finally, the CMD ["node", "source/server.js"] command specifies the command to run when the container starts, which in this case is node source/server.js.

References:

Dockerfile Reference - WORKDIR

The developer can use the Cisco DevNet API documentation to get detailed information on how to use the API for automated data collection from Webex. The API documentation includes comprehensive guides, usage examples, and authentication methods such as HTTP basic authentication. This resource helps developers understand the data formats (JSON or XML) and provides code snippets and best practices for implementation. Cisco DevNet API documentation is designed to assist developers in integrating their applications with Cisco's APIs effectively.

RFC 1918 defines private IP address ranges for use within private networks. The address space 172.16.0.0 to 172.31.255.255 is designated as private and falls under class B.

Class B Address Space: The range 172.16.0.0 to 172.31.255.255 is a private IP address range designated for class B networks.

Subnet Mask: A subnet mask of 255.255.0.0 (/16) is commonly used within this range to create subnets.

References:

RFC 1918 Address Allocation: RFC 1918

Agile:

Optimization of the development process

Focused on the processes of a specific team

Lean:

Optimization of the production process

Focused on the processes of an organization

Agile Methodology:

Optimization of the Development Process: Agile focuses on improving and optimizing the software development process through iterative and incremental development, continuous feedback, and adapting to changes quickly.

Focused on the Processes of a Specific Team: Agile practices are typically implemented within specific development teams, emphasizing collaboration, flexibility, and team autonomy.

Lean Methodology:

Optimization of the Production Process: Lean aims to streamline the production process by eliminating waste, improving efficiency, and delivering value to the customer with the least amount of resources.

Focused on the Processes of an Organization: Lean principles can be applied across the entire organization, not just within individual teams, to improve overall processes and workflow efficiency.

References:

Cisco DevNet Associate Certification Guide, Sections on Agile and Lean methodologies

Official documentation and resources on Agile and Lean software development practices

"The Lean Startup" by Eric Ries (for Lean principles)

"Agile Software Development with Scrum" by Ken Schwaber and Mike Beedle (for Agile principles)

Therefore, the correct mapping is:

Agile:

Optimization of the development process

Focused on the processes of a specific team

Lean:

Optimization of the production process

Focused on the processes of an organization

The Cisco Finesse platform is designed to provide a customizable interface for contact center agents and supervisors. One of its key characteristics is the ability to invoke services based on network-triggered events, allowing for dynamic and responsive workflows within the contact center environment.

In Test-Driven Development (TDD), the process starts with writing tests before writing the actual code. The primary purpose of running tests before writing the code is to ensure that the tests fail initially. This failure demonstrates that the tests are correctly identifying the absence of the desired functionality or the presence of bugs. Once the tests are verified to fail for the expected reasons, the developer then writes the minimal code necessary to pass the tests, ensuring that the new functionality works as intended and that the codebase is continuously tested.

References:

Test-Driven Development by Example

Cisco DevNet Associate Certification Guide

The unified diff format is used to display differences between two files. The content of the file2.py file shows the added lines in the comparison.

Unified Diff Format: The format uses + to indicate lines added in file2.py and - to indicate lines removed.

Line Addition: Line 93 of file2.py has the 'DEVICE-STATS' line, as indicated by the + symbol in the diff output.

References:

Understanding Unified Diff Format: Unified Diff

synchronous: Code execution must wait for an API call to return before continuing.

asynchronous: Code execution does not need to wait for an API call to return before continuing.

REST: Data is called indirectly using generic HTTP methods such as GET, POST, PUT, and DELETE.

RPC: Calls to request a service from a remote server must execute the same way as a request to the local system.

Comprehensive Detailed Step by Step Explanation with References

Synchronous:

Explanation: In a synchronous API call, the client must wait for the server to process the request and return a response before it can proceed with further execution.

Mapping: "Code execution must wait for an API call to return before continuing."

Asynchronous:

Explanation: In an asynchronous API call, the client can continue processing other tasks while waiting for the server to respond. This improves the efficiency and responsiveness of the application.

Mapping: "Code execution does not need to wait for an API call to return before continuing."

REST (Representational State Transfer):

Explanation: REST is an architectural style for designing networked applications. It relies on a stateless, client-server communication protocol, typically HTTP. RESTful APIs use standard HTTP methods (GET, POST, PUT, DELETE) to perform operations on resources.

Mapping: "Data is called indirectly using generic HTTP methods such as GET, POST, PUT, and DELETE."

RPC (Remote Procedure Call):

Explanation: RPC is a protocol that one program can use to request a service from a program located on another computer in a network. The calls are made in the same way as a local function call.

Mapping: "Calls to request a service from a remote server must execute the same way as a request to the local system."

References:

Cisco DevNet Associate Certification Guide, Sections on API styles and their characteristics

Official Cisco documentation on RESTful and RPC APIs

General programming resources on synchronous vs. asynchronous API calls

Therefore, the correct mapping is:

synchronous → "Code execution must wait for an API call to return before continuing."

asynchronous → "Code execution does not need to wait for an API call to return before continuing."

REST → "Data is called indirectly using generic HTTP methods such as GET, POST, PUT, and DELETE."

RPC → "Calls to request a service from a remote server must execute the same way as a request to the local system."

A router is a network component that enables communication between different broadcast domains by forwarding data packets between them based on their IP addresses.

Broadcast Domains: A broadcast domain is a network segment where a broadcast frame is forwarded to all devices.

Router Function: Routers separate broadcast domains, allowing communication between them by routing packets based on their destination IP addresses.

References:

Network Components: Routers and Broadcast Domains

The issue described indicates that HTTPS (port 443) access is not working for one specific server (172.16.50.3) in the network farm, while it works for the others. This suggests that the transport port (port 443) might be blocked or filtered for this particular server.

Transport Port Blocking: Network firewalls or security groups might block specific ports for certain IP addresses.

Server Configuration: The server might not have the necessary configuration to accept HTTPS connections on port 443.

Troubleshooting: Verifying firewall rules, security group settings, and server configurations can help identify and resolve the issue.

References:

Network Troubleshooting Guide: Troubleshooting Network Issues

In REST architecture, the stateless constraint indicates that no client context should be stored on the server between requests. Each request from the client to the server must contain all the information needed to understand and process the request.

Stateless: Ensures that each request is independent and contains all necessary information.

Uniform interface: Defines a standard way of interacting with resources.

Cacheable: Responses must define whether they are cacheable to improve performance.

Client-server: Separates the client and server roles.

In the exhibit, the unified diff output shows changes made to the single_request_timeout method in a Python script. The modifications include:

Removing the assert statement that checks if the value is None or greater than 0.

Adding a raise ValueError statement to ensure that the single_request_timeout must be a positive integer if the value is not None.

These changes can be seen in the sections labeled with @@ -160,11 +160,12 @@ indicating the lines in the original and modified files. The lines starting with - indicate removed lines, and those starting with + indicate added lines. This type of change is typical in code updates to improve validation and error handling.

There are two primary types of NAT (Network Address Translation) used in networking:

Static NAT: Maps a single private IP address to a single public IP address. This type of NAT is useful when you want a specific internal device (like a server) to be accessible from the internet using a consistent public IP address.

Dynamic NAT: Maps a private IP address to a public IP address from a pool of available public IP addresses. This type of NAT is used when you want internal devices to access the internet but do not require a consistent public IP address for each internal device.

Other types mentioned (Normal NAT, Multicast NAT, Router NAT) are not standard terms or widely recognized types of NAT.

1 – D, 2 – A, 3 – H, 4 – F, 5 – G, 6 – E, 7 – C, 8 – B

Test-driven development (TDD) is a software development process where the developer first writes a test for a new function, then writes the code to pass the test, and finally refactors the code. The steps in TDD are:

Write a Failing Test Case: Before any code is written, a test case is created to define the desired functionality.

Write Code to Pass the Test: The minimal amount of code necessary to pass the test is written.

Refactor: The code is refactored for optimization and improvement while ensuring that the tests still pass.

A firewall is a network device that monitors incoming and outgoing traffic and decides whether to allow or block specific traffic based on a defined set of rules.

Function of a Firewall:

Traffic Monitoring: It continuously monitors all traffic passing through it.

Rule-Based Filtering: It applies predefined security rules to allow or deny traffic.

Protection: It protects networks from unauthorized access and cyber threats.

Comparison with Other Devices:

Switch: A network device that connects devices within a LAN and uses MAC addresses to forward data to the correct destination.

Load Balancer: Distributes network or application traffic across multiple servers to ensure no single server becomes overwhelmed.

Reverse Proxy: A server that sits in front of web servers and forwards client requests to those web servers.

Therefore, a firewall is the correct answer because it specifically monitors and filters network traffic based on security rules.

References:

Cisco Firewalls Overview: Cisco Firewall Products

Layer 2 switches use MAC (Media Access Control) addresses to direct packet transmission to the intended recipient.

MAC Address: A unique identifier assigned to network interfaces for communication on the physical network segment.

Switching: Layer 2 switches maintain a MAC address table to keep track of which MAC addresses are associated with which ports, enabling them to forward frames to the correct destination port.

1 – D, 2 – C, 3 – A, 4 – B

Cisco DNA Center is a network management and command center for enterprise networks, providing network controller-level management features. It offers capabilities such as automation, assurance, fabric provisioning, and policy-based segmentation, making it a comprehensive solution for managing and optimizing network performance and operations. Cisco DNA Center is part of the broader Cisco Digital Network Architecture (Cisco DNA), designed to facilitate the efficient and automated management of networks. More information can be found on the Cisco DNA Center product page.

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Generating log bundles is a resource-intensive task that can cause high CPU utilization on the Cisco DNA Center. When the CPU spikes, it can affect the performance of other critical tasks, such as forwarding voice IP packets, leading to delays and poor voice quality. This is especially noticeable during business hours when network utilization is high, and voice traffic is sensitive to latency and jitter. More details can be found in Cisco DNA Center documentation on Managing Logs and System Performance.

The Cisco DevNet Sandbox is a resource provided by Cisco that allows developers to access a variety of Cisco products in a development lab environment. This resource enables users to explore, learn, and build applications using Cisco APIs. The sandbox environment is equipped with pre-configured topologies and a range of Cisco technologies, offering a safe and secure space to experiment without the need for physical hardware.

DevNet Sandbox: Provides access to virtual environments for learning and development.

DevNet Communities: Are for discussions and collaboration among developers.

DevNet Code Exchange: Offers code repositories and examples for various Cisco technologies.

DevNet Automation Exchange: Focuses on automation scripts and tools shared by the community.

By segmenting the network into separate subnets for clients and servers, you can control the types of traffic that flow between these segments using access control lists (ACLs) and firewall rules. This can enhance security by limiting access to critical server resources and reducing the risk of unauthorized access.

Subnets will split domains to limit failures (Option C):

Segmenting the network into different subnets helps contain network issues within a specific segment, preventing them from affecting the entire network. This approach improves network stability and reliability, as issues in the client subnet will not impact the server subnet and vice versa.

References:

Cisco Subnetting and Network Segmentation

Cisco Router and ACL Configuration Guide

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Edge computing is a distributed computing paradigm that brings computation and data storage closer to the sources of data. This helps to:

Reduce Latency: By processing data closer to where it is generated, edge computing reduces the time taken for data to travel to a central server and back. This is especially important for applications requiring real-time or near-real-time responses.

Optimize Bandwidth: Reducing the amount of data sent to a central data center can conserve bandwidth and lower costs.

Enhance Security and Privacy: Processing data locally can enhance security and privacy by minimizing the exposure of data during transmission.

1 – D, 2 – B, 3 – C, 4 – E, 5 – A

When you execute the command git clone ssh://john@example.com/path/to/my-project_git, the git clone command is used to create a local copy of a remote repository. In this case, it is accessing the repository over SSH (Secure Shell). The URL ssh://john@example.com/path/to/my-project_git specifies the location of the remote repository.

git clone is a Git command that creates a copy of an existing repository in a new directory.

The local copy will contain all the history and branches of the original repository.

The repository will be cloned into a directory named after the remote repository, which in this case would be "my-project".

ï‚· Understand the JSON Structure: The JSON data given in the exhibit consists of an array of objects. Each object has a type and an items key. The items key contains an array of objects, each with a color and another items key, which is an array of strings representing items of that color.

ï‚· Analyze the Python Code: The Python code provided is:

print(filter(lambda l: l['type'] == 'fruit', vegetables)[0]['items'][0]['items'][0])

Break Down the Code:

filter(lambda l: l['type'] == 'fruit', vegetables): This line filters the JSON array vegetables to include only objects where the type is 'fruit'.

filter(...)[0]: After filtering, this selects the first object in the filtered list, which is the fruit object.

['items'][0]: This accesses the first item in the items array of the fruit object. In this case, it refers to the object where color is "green".

['items'][0]: This accesses the first item in the items array of the green object, which is "kiwi".

Evaluate the Code:

The first object of type fruit in the JSON is found.

The first item in the items array for fruit with the color green is selected.

The first item in this nested items array is "kiwi".

Therefore, the output of the given Python command is "Kiwi".

References:

Python documentation on filter: Python Docs - Filter

JSON structure understanding from DevNet Associate study materials on API interactions and data parsing.

Test-Driven Development (TDD) is a software development approach where tests are written before writing the actual code. The steps involved in TDD are:

Write a test for the new functionality.

Run the test and see it fail (because the functionality is not yet implemented).

Write the minimum code necessary to make the test pass.

Refactor the code while keeping the test passing.

Option B is the correct answer because refactoring code while it is covered by existing tests is a key aspect of TDD. The existing tests ensure that the functionality remains correct even after refactoring.

References:

Cisco DevNet Associate Exam Topics: Software Development and Design (understanding TDD methodology)

"Test-Driven Development by Example" by Kent Beck (standard reference on TDD)

Functions in programming are a fundamental concept that provide several key benefits:

Modularity: By breaking down a program into smaller, manageable functions, it becomes easier to understand, debug, and maintain.

Reusability: Functions allow code to be reused across the program, reducing redundancy.

Abstraction: Functions can abstract complex operations into a simple function call, making the code easier to read and understand.

Testing: Functions can be tested individually, which simplifies the process of testing the overall program.

1 – B, 2 – D, 3 – A, 4 – C

A default gateway serves as an access point or IP router that a networked computer uses to send information to a computer in another network or the internet. It is essentially the forwarding node that routes traffic from a local network to other networks. When an IP packet's destination is not within the local network and no specific route is defined in the routing table, the packet is sent to the default gateway.

Injection attacks occur when untrusted data is sent to an interpreter as part of a command or query. The attacker's hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization. Common types of injection attacks include SQL injection, command injection, and LDAP injection. These types of attacks exploit vulnerabilities in how an application processes input data, allowing attackers to inject malicious commands or queries into the system.

YANG model-driven programmability allows for the configuration of devices using data models. In NX-OS, this includes both native and OpenConfig-based models.

YANG Models: These are used to model configuration and state data for network devices. Native models are specific to the vendor, while OpenConfig models are vendor-neutral.

Configuration Management: YANG models facilitate consistent and programmable configuration of network devices, which can be done through APIs like NETCONF or RESTCONF.

Virtual machines (VMs) run directly on a hypervisor, which abstracts and manages the underlying hardware resources.

Hypervisor: A hypervisor, also known as a Virtual Machine Monitor (VMM), allows multiple VMs to run on a single physical machine by providing an abstraction layer between the VMs and the hardware.

VMs: Each VM operates as a separate entity with its own operating system and applications, isolated from other VMs.

YANG (Yet Another Next Generation) is a data modeling language used to model configuration and state data manipulated by the NETCONF protocol. Here are two advantages of YANG-based approaches for infrastructure automation:

Multi-platform vendor abstraction (Option B):

YANG provides a standardized way to model configuration and state data, enabling multi-platform vendor abstraction. This means that network engineers can write configurations and management scripts that work across different network devices from different vendors, as long as they adhere to the YANG model. This reduces the complexity and increases the interoperability in multi-vendor environments.

Designed to reflect networking concepts (Option C):

YANG is specifically designed to reflect networking concepts and constructs, making it intuitive and effective for defining network configurations and states. The hierarchical structure of YANG models aligns well with the structure of network configurations, allowing for precise and clear definitions of network elements and their relationships.

References:

Cisco YANG Overview

IETF YANG

Cisco Advanced Malware Protection (AMP) provides APIs that can be used to obtain a list of vulnerable software on user devices. AMP for Endpoints offers extensive capabilities for threat detection and response, including the ability to query for vulnerabilities. These APIs allow developers to integrate vulnerability information into their applications, enabling proactive security measures. Detailed information on using AMP APIs can be found in the Cisco AMP for Endpoints API documentation.

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A – E, B – D, C – B, D – C, E – A, F – F

For Basic Authentication in REST APIs, the Base64 encoded credentials must be included in the header of the HTTP request. The correct method is to include the following header in the request:

Authorization: Basic am9objowMTlzNDU2Nzg=

References: Cisco DevNet Associate Certification Guide, Chapter on REST API Authentication methods.

Firewalls are used to control incoming and outgoing network traffic based on predetermined security rules, primarily by limiting traffic to only the necessary ports for an application.

Port Filtering: Firewalls can block or allow traffic based on port numbers, thus limiting exposure to only those ports required by the application, enhancing security.

Security: This helps to protect the application from unauthorized access and potential attacks by reducing the attack surface.

The HTTP status code 200 indicates successful execution of a request.

Status Code 200:

Meaning: OK - The request has succeeded. The meaning of the success depends on the HTTP method:

GET: The resource has been fetched and is transmitted in the message body.

HEAD: The headers are in the message body.

POST: The resource describing the result of the action is transmitted in the message body.

TRACE: The message body contains the request message as received by the server.

Comparison with Other Codes:

404 - Not Found: The server can’t find the requested resource.

405 - Method Not Allowed: The request method is known by the server but is not supported by the target resource.

500 - Internal Server Error: The server encountered an unexpected condition that prevented it from fulfilling the request.

Thus, the status code 200 indicates that the request was successful.

References:

HTTP Status Codes: MDN Web Docs

A network interface hardware address, also known as a MAC (Media Access Control) address, is a unique identifier assigned to network interfaces for communications on the physical network segment.

Domain name: A human-readable address for network resources.

IP address: A logical address used for identifying devices on a network.

Workstation name: A human-readable name assigned to a computer.

MAC address: The correct answer, which is a hardware address assigned to a network interface.

A MAC (Media Access Control) address is a unique identifier assigned to a network interface card (NIC) for communications at the data link layer of a network segment. MAC addresses are used within local area networks (LANs) to ensure that data packets are delivered to the correct hardware device. Every network interface on a device, such as a computer, router, or switch, has a unique MAC address.

Test-Driven Development (TDD) is a software development approach where tests are written before the code that needs to be tested.

TDD Process:

Write a Test: Start by writing a test for a new feature or functionality.

Run the Test: Run the test, which should fail initially since the code hasn’t been written yet.

Write Code: Write the minimum amount of code required to pass the test.

Run Tests Again: Run the tests again to ensure they pass.

Refactor: Refactor the code while ensuring the tests still pass.

Advantages:

Early Bug Detection: Bugs are detected early in the development cycle.

Better Design: Promotes writing cleaner, more modular code.

Documentation: The tests themselves serve as documentation for the code.

Writing and running tests before writing the actual code ensures that the code meets the specified requirements and functions correctly.

References:

TDD Overview: Test-Driven Development

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Cisco DNA Center provides a REST API that allows users to interact with the network devices managed by the platform. To retrieve a list of network devices, an HTTP GET request is sent to the endpoint https://DNA-c_API_ADDRESS/api/v1/network-device/ . The response from this request contains a list of network devices in JSON format. This API endpoint allows for programmatic access to network device data, facilitating automation and integration with other systems. Detailed information about the Cisco DNA Center APIs can be found in the Cisco DNA Center API documentation.

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Clients make several types of queries to DNS servers. The two relevant types here are:

AAAA: This query type requests the IPv6 address associated with a domain name.

PTR: This query type is used for reverse DNS lookups, where it maps an IP address to a domain name.

AAAA (Quad-A) records store IPv6 addresses of a domain.

PTR (Pointer) records are used in reverse DNS lookups to map IP addresses to the corresponding domain names.

References: DNS and BIND by Cricket Liu and Paul Albitz, Cisco DevNet Associate Certification Guide.

Artifact repositories play a crucial role in Continuous Integration/Continuous Deployment (CI/CD) pipelines by:

Storing Build Artifacts: They store files needed during the build process, such as dependencies, and files generated during the build process, such as binaries.

Providing Traceability: They offer traceability and versioning of binary files, which is essential for managing builds and releases.

Search and Management: They allow developers to search and manage binary files efficiently, ensuring that the correct versions of dependencies are used.

DevOps emphasizes collaboration between development and operations teams, breaking down organizational silos to improve workflow and communication (C). Additionally, DevOps focuses on automating processes to increase efficiency, reduce manual effort, and minimize errors, often prioritizing automation over extensive documentation (E).

References:

Cisco DevNet Associate Exam Topics: DevOps Practices and Principles (understanding the core principles of DevOps)

"The Phoenix Project" by Gene Kim, Kevin Behr, and George Spafford (explains the importance of cross-functional teams and automation in DevOps)

1 – B, 2 – E, 3 – C, 4 – D, 5 – A

When a REST API limits the amount of data returned in a response, it often uses pagination. Pagination breaks the response into smaller, more manageable chunks, allowing the client to retrieve the data in multiple requests.

Pagination: Limits the number of records returned in a single response, requiring additional requests to retrieve subsequent records.

Payload limit: Restricts the size of the response payload but is not the specific feature for controlling record count.

Rate limiting: Controls the number of requests a client can make in a given time period.

Service timeouts: Define how long the server will wait for a request to complete before timing out.

The script provided in the exhibit shows the following steps:

It configures a loopback interface (interface loopback 5; no shut).

It retrieves the interface details and parses the JSON output to list interfaces that are up.

Therefore, the correct answers are: A. Configure interface loopback 5. C. Show only the interfaces in the up status.

Option A correctly creates a handle instance using the UcsHandle class from the UCS SDK in Python. The correct instantiation requires providing the IP address, username, password, port number, and secure connection parameters as per the documented API.

The correct code snippet is:

from ucsmsdk.ucshandle import UcsHandle

handle = UcsHandle("10.1.2.254", "admin", "password", port="443", secure=True)

This snippet matches the API documentation requirements:

ip: The IP or hostname of the UCS Server.

username: The username as configured on the UCS Server.

password: The password as configured on the UCS Server.

port: The port number to be used during the connection.

secure: True for a secure connection.

References:

UCS Python SDK Documentation (provides details on how to use UcsHandle)

Cisco DevNet Associate Exam Topics: Infrastructure and Automation (understanding how to use APIs and SDKs for automation)

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When authenticating a RESTCONF API session with a router running Cisco IOS XE software, basic authentication is commonly used. Basic authentication involves sending the username and password in the HTTP header encoded in base64 format. This method is straightforward and widely supported, though it is less secure compared to token-based authentication and should be used with HTTPS to ensure the credentials are encrypted in transit.