100-490 Supporting Cisco Routing & Switching Network Devices (RSTECH) Question and Answers

To gain console access to a Cisco switch, two types of ports on a laptop can be used: DB-9 and USB. The DB-9 port is a traditional serial port that is often used with a DB-9 to RJ-45 console cable to connect to the switch’s console port1. However, as modern laptops may not have a DB-9 port, a USB to Serial adapter can be used instead, which creates a virtual COM port that can be used to connect to the switch1. The USB port can also be used directly if the switch has a USB console port, which is common on newer Cisco devices. These ports allow for direct physical connection to the switch for configuration and management purposes. References := Access the CLI via PuTTY using a Console Connection on 300 and 500 Series Managed Switches - Cisco, How to connect Switch with console port - Cisco Learning Network

The Cisco Nexus 3432D-S and Cisco Nexus 3408-S are part of the Cisco Nexus 3400 Series switches that support 400-Gbps Ethernet ports. The Cisco Nexus 3432D-S is designed with 32 ports of 400G, providing high-density and high-throughput capabilities1. The Cisco Nexus 3408-S offers flexibility with 100G or 400G Line-Card Expansion Modules (LEMs), allowing for configurations with 32 ports of 400G2. These switches are engineered for data centers requiring high performance, low latency, and power efficiency, with the Cisco Nexus 3432D-S offering industry-leading performance-per-watt power efficiency at low latency1.

The Cisco CPAK-100G-SR4 module is designed to support Multimode Fiber (MMF) cable. It is specifically engineered for high-bandwidth 100G optical links and supports link lengths of up to 70 meters over OM3 and 100 meters over OM4 Multimode Fiber with MPO connectors. This module is well-suited for short-range, high-speed data communications and data center applications where Multimode Fiber is typically used due to its ability to handle the large amount of data traffic over relatively short distances. References := Cisco CPAK 100GBASE Modules Data Sheet

Questions no: 12 Verified Answer: = B. switch-to-router, E. switch-to-server Comprehensive and Detailed Step by Step Explanation: = RJ-45 straight-through cables are used to connect different types of devices in a network. The standard practice is to use straight-through cables for connections that are unlike to each other, such as:

Switch-to-Router: A switch connects devices within a network by using MAC addresses to forward data to the correct destination. A router, on the other hand, connects multiple networks and uses IP addresses to determine the best path for the data packets. Connecting a switch to a router requires a straight-through cable because they are different types of devices12.

Switch-to-Server: Servers are the powerful computers that provide resources, data, services, or programs to the client machines in the network. When connecting a switch to a server, a straight-through cable is used because the switch and the server are different types of devices with different functions within the network12.

References := Guru99, TheTechMentor

The image provided shows a networking device connected to a laptop via a console cable. Based on the visual indicators and standard port designs:

C. 3 is a USB 5-pin mini USB Type B port: The port labeled “3” on the laptop is smaller than a standard USB Type A port, which suggests it is a mini USB Type B port, commonly used for connecting to networking devices for console access.

E. 2 is a USB 5-pin mini USB Type B to USB Type A console cable: The cable labeled “2” has one end that fits into the mini USB Type B port on the laptop (as identified in point 1), and the other end, which is not clearly visible in the image, is inferred to be a USB Type A connector that would typically connect to a computer’s USB port.

IPv4 addresses consist of four octets, each ranging from 0 to 255. The addresses are used to uniquely identify devices on a network.

A. 255.255.255.255 is reserved for broadcast messages to all hosts on the local network, so it cannot be assigned to a single host.

B. 10.1.1.20 falls within the range of private IP addresses (10.0.0.0 to 10.255.255.255) and can be assigned to a host within a private network.

C. 0.0.0.0 is used to denote an unknown or non-applicable target address, often used as a default route, and cannot be assigned to a host.

D. 192.168.10.15 is also within the range of private IP addresses (192.168.0.0 to 192.168.255.255) and can be assigned to a host within a private network.

E. 292.10.3.4 is not a valid IPv4 address because the first octet exceeds the maximum value of 255.

References :=

IPv4 Addressing

Valid IP Address

IP Address Validation

SmartJacks are specialized devices used in telecommunications, particularly for T1/E1 lines. Here's why the correct answers make sense:

Signal Conversion: SmartJacks can convert between different signaling types (e.g., AMI to B8ZS). This is necessary because different telecommunication lines may use varying signaling standards.exclamation

Signal Regeneration: As signals travel over long distances, they can weaken and degrade.expand_more SmartJacks help regenerate the signal, ensuring that it maintains its strength and integrity throughout the transmission.expand_more

Why other options are incorrect:

Concentration point: SmartJacks are not primarily used as concentration points for dial-in/out connections.exclamation This function is typically handled by modems or other specialized devices.exclamation

Layer 2 operation: SmartJacks primarily operate at Layer 1 (Physical Layer) of the OSI model, focusing on the physical transmission of signals.

Channel Testing: While some SmartJacks may offer some basic channel testing capabilities, their primary functions are signal conversion and regeneration.

References:

SmartJack (Wikipedia): https://en.wikipedia.org/wiki/Smartjack

A. Correct. SSH, or Secure Shell, is indeed a protocol that provides a secure remote access connection to network devices. It encrypts the data to ensure secure transmission over insecure networks like the internet1.

C. Correct. Telnet connections are not secure and are terminated when a router reboots. This is because Telnet does not have any mechanism to maintain the connection in case of network interruptions or device reboots1.

B, D, and E are incorrect because: B. SSH uses TCP port 22 by default, not port 23, which is used by Telnet1. D. Telnet does not provide a secure connection; it transmits data in plain text, which can be intercepted easily1. E. SSH is preferred over Telnet for security reasons because it provides encrypted connections and authentication mechanisms, which Telnet does not1.

References :=1: GeeksforGeeks - Difference between SSH and Telnet 2: phoenixNAP - Telnet vs. SSH: How Is SSH Different From Telnet? 3: Guru99 - Telnet vs SSH – Difference Between Them 4: Difference Between - Difference Between Telnet and SSH

TFTP, or Trivial File Transfer Protocol, is a simple protocol used for transferring files. Unlike other file transfer protocols, TFTP operates on top of the User Datagram Protocol (UDP), which is a connectionless protocol. This means that TFTP does not establish a persistent connection between the client and server, and it does not guarantee reliable delivery of packets, error checking, or correction. TFTP is typically used in scenarios where simplicity and minimal memory footprint are more critical than the need for reliable delivery, such as when booting a device over a network123. References := Wikipedia, GeeksforGeeks, PyNet Labs

The address that facilitates the routing of packets over an IP network is the network address. In the context of IP networking, this refers to the IP address, which is used to identify each host on a network and to determine the best path for data packets to travel from their source to their destination. Routers use IP addresses to make decisions about where to forward packets so that they reach the correct destination. The network layer of the OSI model, where IP operates, is responsible for this routing process123.

The other options listed do not facilitate routing in the same way:

Physical (A) and MAC (D) addresses are used at the data link layer to deliver packets on the same local network.

Transport (B) refers to the transport layer, which is responsible for end-to-end communication and data flow control but does not route packets over an IP network.

The correct IPv6 address notation follows the format of eight groups of four hexadecimal digits, separated by colons. The address must have exactly eight groups unless it uses the double colon (::) to represent consecutive groups of zero value. The double colon can only appear once in an address to avoid ambiguity.

Option A is incorrect because it includes a subnet mask (/128) which is not part of the actual address notation. Option B is incomplete as it does not contain enough groups and ends with a single colon. Option C has too many groups (nine instead of eight) and is therefore not a valid IPv6 address. Option D is the correct notation with eight groups of four hexadecimal digits, where necessary leading zeros are included.

References :=

IPv6 Address Types, Notation, and Structure Explained1.

IPv6 address formats - IBM2. =========================

A DTE (Data Terminal Equipment) device is an end instrument that converts user information into signals or reconverts received signals. In the context of networking, a router can be considered a DTE device because it is typically at the user end of a user-network interface and serves as a data source or destination. It communicates with the data circuit-terminating equipment (DCE), such as a modem, to send and receive data across the network345.

References := Wikipedia, Techopedia, Network Encyclopedia

The show ip interface brief command provides a concise summary of the status and IP addressing configuration of interfaces on a Cisco router or switch. Here's what it displays:

Interface: The name of the interface (e.g., FastEthernet0/0, GigabitEthernet1/1).

IP Address: The Layer 3 IP address assigned to the interface (if any).

OK? Indicates the IP layer status of the interface (YES if operational, NO if not).

Method: How the IP address was configured (manual or DHCP).

Status: The Layer 1 status of the interface (up or down).

Protocol: The Layer 2 status of the interface (up or down).

Why other options are incorrect:

Layer 2 address: The show ip interface brief command does not directly display Layer 2 (MAC) addresses. You can use the show interface command for that.

Keepalive: Keepalives are used in some routing protocols but are not generally reflected in the output of the show ip interface brief command.

Encapsulation type: Encapsulation information is also not typically included in the show ip interface brief output.

References:

Cisco IOS show ip interface brief command: [invalid URL removed]

Example output of show ip interface brief: https://www.cisco.com/E-Learning/bulk/public/tac/cim/cib/using_cisco_ios_software/cmdrefs/show_ip_interface.

The type of memory used to store Cisco IOS Software permanently is flash memory. Flash memory is non-volatile, meaning it retains its content even after the device is powered down or restarted. It is commonly used in Cisco devices to store one or more Cisco IOS software images, as well as other files such as backup configuration files. This allows the device to reload the operating system after a reboot without the need to retransfer the IOS image

The command that returns the user to the main configuration prompt from the interface configuration prompt is exit. When you are in interface configuration mode on a Cisco device and you want to return to the global configuration mode, you use the exit command. If you want to go all the way back to privileged EXEC mode, you would use the end command or press Ctrl-Z1.

The configuration register on Cisco routers and switches controls specific bootup behaviors. Here's how to modify it:

1. In ROMmon Mode:

rommon>confreg 0x2102 : This command is used when the device is in ROMmon mode (a basic operating system loaded when the full Cisco IOS cannot be found). ROMmon offers limited functionality and is often used for troubleshooting or password recovery.

2. In Global Configuration Mode:

router(config)#config-register 0x2102 : This command is used from within the Cisco IOS itself when you have normal access to the router. You would enter privileged EXEC mode and then global configuration mode to use it.

Importance of Configuration Register Settings:

The most common reasons to modify the configuration register are:

Password Recovery: Setting the configuration register to 0x2142 tells the router to ignore the startup configuration (stored in NVRAM), allowing you to bypass password protection.

Changing Boot Behavior: Settings can control the boot sequence, such as specifying where the Cisco IOS image should be loaded from.

References:

Cisco Configuration Register: https://www.cisco.com/c/en/us/support/docs/routers/10000-series-routers/50421-config-register-use.html

Understanding the Configuration Register (Cisco): https://networklessons.com/cisco/ccna-routing-switching-icnd1-100-105/configuration-register-cisco-ios

 The decompressed form of Cisco IOS Software and the running configuration are stored in DRAM (Dynamic Random-Access Memory) on Cisco devices. DRAM is used as the main memory for the device, where the operating system runs and the running configuration is stored. When a Cisco device boots up, the IOS image is decompressed and loaded into DRAM, and the running configuration is also held in this memory type. It’s important to note that DRAM is volatile memory, which means its contents are lost when the device is powered off or restarted12. References := Maintaining System Memory Configuration Guide, Cisco IOS Release 15M&T - Cisco, Types of memory on a Cisco device - Study-CCNA

When you initially log in to a Cisco router, the default operating mode is user EXEC mode. This mode provides a limited set of basic monitoring commands but does not allow for any configuration changes to the router’s settings. To make configuration changes, you must enter privileged EXEC mode (often accessed by the enable command), which offers a wider range of commands that allow for the viewing and modification of the configurationGlobal configuration mode is accessed from privileged EXEC mode to modify the router’s configuration, and ROM monitor mode is a low-level mode used mainly for recovery purposes1.