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

This configuration describes acrossover cable. A crossover cable is used to connect two similar devices directly, such as two computers or two switches, without the need for an intermediate device like a router. The wires at one end of a crossover cable are in reverse sequence to the wires at the other end, which allows the transmit and receive signals to beproperly aligned between the two devices.This is different from a straight-through cable, where the wire sequence is the same at both ends1.

The line speed of a DS0 in North America is:

C. 64 kbps

DS0, or Digital Signal 0, is a digital signaling standard in telecommunications characterized by its transmission rate of 64 Kbps. It is the basic unit of data in digital networks and is used to transmit a single voice channel or data

A Wide Area Network (WAN) connection typically involves several components that work together to enable data communication over large distances. Two key components of a WAN connection are:

• CSU/DSU (Channel Service Unit/Data Service Unit): This device acts as a gateway between the local area network (LAN) and the WAN. It converts the digital signals used in the LAN to the signals used in the WAN, which are often analog12.
• Router: A router is used to connect multiple networks together and direct data traffic. In the context of a WAN, routers are responsible for determining the best path for data to travel across the network12.

References := Spiceworks, Cisco

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. =========================

The address that facilitates the routing of packets over an IP network is thenetwork 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)andMAC (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.

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

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

• A. 255.255.255.255is reserved for broadcast messages to all hosts on the local network, so it cannot be assigned to a single host.
• B. 10.1.1.20falls 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. 0.0.0.0is used to denote an unknown or non-applicable target address, often used as a default route, and cannot be assigned to a host.
• D. 192.168.10.15is 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. 292.10.3.4is not a valid IPv4 address because the first octet exceeds the maximum value of 255.

References:=

• IPv4 Addressing
• Valid IP Address
• IP Address Validation

Theshow cellular unit networkcommand in Cisco IOS is used to view detailed information about the cellular modem and the network it's connected to. Here's the type of information this command usually displays:

• Network Status:Whether the device is registered on the cellular network.
• Carrier Information:The name of the cellular network provider.
• Technology:The cellular technology in use (e.g., 3G, 4G/LTE).
• Signal Strength:Signal strength indicators like RSSI and RSCP.
• Cell Site Information:Data about the cell tower or base station the device is connected to.
• IP Address:The IP address assigned to the cellular interface.

Why other options are less likely:

• show cellular unit radio:Provides information about the radio module itself, such as its state and power levels.
• show cellular unit hardware:Focuses on hardware-level information of the cellular unit.
• show cellular unit profile:Displays configuration details of the cellular profile used to connect to the network.

References:

• Cisco command documentation for differentshow cellularoptions:https://www.cisco.com/c/en/us/td/docs/routers/wireless-wan/Cisco-Catalyst-Cellular-Gateways/cisco-cellular-gateways-command-reference-guide/m-show_commands.pdf

The command show file system is used on Cisco devices to display a list of all the file systems available. This command provides information about each file system, including its name, size, free space, and file system type (such as flash or nvram). It’s a useful command for network administrators to manage and navigate through different storage areas on Cisco devices, ensuring they can access and maintain the device’s file structure effectively. References := File System Commands on Cisco IOS XR Software - Cisco, Working with the Cisco IOS File System, Configuration Files, and Software Images

When deploying Cisco Catalyst 3850 Series switches, there are two modes of operation to choose from:Install modeandBundle mode. Install mode is the default mode for the switch and uses a package-provisioning file namedpackages.confto boot the switch.It allows for a more complete set of features and requires fewer resources upon boot1. Bundle mode, on the other hand, is similar to using traditional monolithic Cisco IOS images to boot the switch.It consumes more memory than Install mode because the packages are extracted from the bundle and copied to the RAM2.Cisco recommends using Install mode for operation due to its efficiency and feature set2.

The configuration register on Cisco devices is a 16-bit value, typically represented in hexadecimal notation (e.g., 0x2102). The lowest four bits (bits 0-3) of this value are designated as the boot field.

The Boot Field's Importance:

The boot field determines how the device will load its operating system (Cisco IOS) during the startup process. Here's a basic breakdown of common boot field values:

• 0x0:Stay at the ROMmon prompt.
• 0x1:Boot from ROM (often used for troubleshooting or recovery).
• 0x2 - 0xF:Load the operating system based on settings in the startup configuration (NVRAM) or from a network server if specified.

Example:

A configuration register value of0x2102indicates that the boot field is0x2(the last digit). This is a common default setting, instructing the device to load the Cisco IOS image from Flash memory.

References:

• Cisco Configuration Register Detailed Explanation:[invalid URL removed]
• Configuration Register Settings (Cisco):https://networklessons.com/cisco/ccna-routing-switching-icnd1-100-105/configuration-register-cisco-ios

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

Thecmdprogram, also known as the Command Prompt, is the primary command-line interface in Windows. It allows you to execute various commands, including thepingcommand, to perform network testing and troubleshooting.

Here's how to usepingin the Command Prompt:

• Open the Command Prompt:Search for 'cmd' in the Windows Start Menu or use the Run dialog (Windows key + R) and type 'cmd'.
• Type thepingcommand:Enterpingfollowed by a space and then either the IP address or hostname you want to test. For instance:ping 8.8.8.8orping www.google.com.
• Press Enter:The Command Prompt will send ping requests and display the results.

Why other options are incorrect:

• Find:The Find utility in Windows is used to search for files and folders based on their content or attributes.
• Start:The Start Menu in Windows provides access to programs, settings, and power options.
• ipconfig:Theipconfigcommand is used to display network configuration information but doesn't directly execute thepingcommand.

References:

• Windows Command Prompt (cmd):https://en.wikipedia.org/wiki/Cmd.exe
• Ping command:https://en.wikipedia.org/wiki/Ping_(networking_utility)

The Cisco Nexus 9300 Series switches are a family of high-performance data center switching products. However, only a specific subset of models within this series supports 400-Gbps Ethernet ports.

Based on the information available online, two models from the Cisco Nexus 9300 Series that offer 400-Gbps Ethernet ports are:

• Cisco Nexus 9316D-GX:This is a 1RU fixed switch that provides 16 ports of 400 Gbps (QSFP-DD) with a non-blocking switch architecture. It's suitable for aggregation, core, or spine applications.
• Cisco Nexus 93600CD-GX:This is also a 1RU fixed switch, but it offers a combination of ports. It includes 28 ports of 100G and 8 ports of 400 Gbps (QSFP-DD) with a non-blocking switch architecture. This model is well-suited for data center Top-of-Rack (ToR), End-of-Row (EoR), and collapsed aggregation and access deployments, particularly when used with Cisco Nexus 2000 Fabric Extenders.

References:

• Cisco Nexus 9000 Series 400G Deployment Guide

The-coption in Xmodem file transfers is used to enable CRC (Cyclic Redundancy Check) for enhanced error checking. Here's why it's the correct answer:

• Error Detection:CRC is a more robust error detection mechanism compared to the standard checksum method used in Xmodem. It provides greater reliability in identifying file corruption during the transfer.
• Flash Memory:Since flash memory on a Cisco router or switch stores critical data like configuration files or the IOS image, ensuring the integrity of transferred files is crucial.

Why other options are incorrect:

• -e, -r, -x:These are not standard Xmodem options for error checking purposes. While some implementations may have custom flags, they are not universally applicable.

Important Note:Xmodem is a legacy protocol that is often replaced by more reliable options like TFTP in modern Cisco devices. However, understanding Xmodem options is still relevant for certain cases or older equipment.

References:

• Xmodem overview:https://en.wikipedia.org/wiki/XMODEM
• Cyclic Redundancy Check (CRC):https://en.wikipedia.org/wiki/Cyclic_redundancy_check

1. It is built on a client-server model architecture and uses separate control and data connections between the client and the server2. Here are the explanations for the correct answers:

•B: The copy running-config ftp: command is used to copy the running configuration from a router to an FTP server or vice versa. This is a common method for backing up and restoring configurations on Cisco devices1.

•E: FTP typically requires authentication, which means a Cisco router acting as an FTP client must be configured with the appropriate username and password to access an FTP server. This ensures secure file transfer and access control1.

The other options are incorrect because:

•A: FTP is not used to load Cisco IOS Software to a router in ROMMON mode; this is typically done using TFTP or Xmodem.

•C: While a router can act as an FTP server, this is not a description of FTP itself.

•D: FTP uses TCP as its transport protocol, not UDP. FTP needs the reliability that TCP provides because it ensures the complete and accurate transfer of files1.

A SmartJack is a type of Network Interface Device (NID) that provides advanced features beyond simple electrical connection. Two of its functions include:

•Regenerating the signal: Similar to a repeater, a SmartJack can buffer and regenerate the signal to compensate for signal degradation that occurs during line transmission. This helps maintain signal integrity over longer distances1.

•Signal conversion: A SmartJack may also provide signal conversion, which involves converting codes and protocols to the type needed by the customer equipment. This can include converting framing types or other signal characteristics to ensure compatibility with the connected devices1.

The other options listed are not primary functions of a SmartJack:

•Operating at Layer 2 of the OSI model © is not a function of a SmartJack; it is a characteristic of network devices like switches and bridges.

•Providing channel testing (D) is not a standard function of a SmartJack; however, SmartJacks enable phone companies to remotely test customer wiring without a site visit2.

•Acting as a concentration point for dial-in and dial-out connections (E) is not a function of a SmartJack; this is typically a function of devices like modems or access servers.

References := Network interface device - Wikipedia, Demarcation Point: Everything You Need To Know