Curious about Actual Cisco CCT Routing & Switching (100-490) Exam Questions?

Correct : D

The tftpdnld command is specifically designed to initiate a TFTP (Trivial File Transfer Protocol) transfer of an image within ROMmon mode on a Cisco device. Here's why it's the correct answer:

ROMmon Functionality: ROMmon (Read-Only Memory Monitor) is a basic operating system mode used when the main Cisco IOS is unavailable. The tftpdnld command works from ROMmon to download a new IOS image.

TFTP Protocol: The tftpdnld command utilizes TFTP, which is a simple and reliable protocol commonly used for transferring Cisco IOS images.

Purpose: The command is used primarily for recovering corrupt images or upgrading to a different IOS version.

Why other options are incorrect:

Xmodem: XMODEM is an older and less reliable file transfer protocol that's less suitable than TFTP for Cisco IOS image transfers.

copy tftp: flash: This command format is used within the Cisco IOS itself, not in ROMmon mode.

copy flash: tftp: This command format would attempt to upload an image from flash memory to a TFTP server, instead of downloading an image.

Correct : C

Straight-through cables are the most common type of Ethernet cable. They're used to connect dissimilar devices, such as a laptop to a router or a switch to a router. The internal wiring of the cable connects the transmit pins on one end to the receive pins on the other end, and vice versa.

Crossover cables were historically necessary to connect similar devices (e.g., router to router, or switch to switch). Modern devices often have auto MDI-X capabilities, allowing them to automatically detect and adjust to straight-through or crossover connections as needed.

Rollover cables have a reversed pinout and are primarily used for console access into Cisco routers and switches.

Fiber cables use fiber optic technology for high-speed, long-distance connectivity.

Cisco Networking Academy: Introduction to Networks Course

Correct : C

The -c option 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.

Xmodem overview: https://en.wikipedia.org/wiki/XMODEM

Cyclic Redundancy Check (CRC): https://en.wikipedia.org/wiki/Cyclic_redundancy_check

Correct : B, E

In the context of IPv4 addresses, a host address is an identifier for a specific device on a network. The addresses 10.1.1.20 and 192.168.10.15 are both within ranges typically reserved for private networks, making them suitable for assignment to host computers within a local network. Address 292.10.3.4 is not a valid IPv4 address because the first octet is beyond the maximum value of 255. Address 255.255.255.255 is reserved for broadcast messages to all hosts on the local network, and 0.0.0.0 is used to denote an unspecified address, often indicating the absence of an IP address123. Reference := IP address, Network address, and Host address Explained, IP address - Wikipedia, Understanding IP Addresses: How IP Addressing Works | ENP

Correct : D

The configuration register on Cisco devices controls how the device boots up. By changing the configuration register to 0x2142, you instruct the router to bypass the startup configuration file stored in NVRAM. This is crucial in the password recovery process because the passwords are stored in this configuration file.

Procedure for Password Recovery:

1. Break the boot sequence: Power cycle the router (turn off/on). During the boot process, send a 'Break' signal to get into ROMmon mode.

2. Change the configuration register: In ROMmon mode, type confreg 0x2142 and reload the router.

3. Boot without startup-config: The router will boot up, ignoring the saved startup configuration, allowing you to enter privileged EXEC mode without a password.

4. Change the password: Access configuration mode (configure terminal), and change the passwords as needed (enable password, enable secret, etc.).

5. Reset the configuration register: Set the configuration register back to its original value (usually 0x2102).

6. Save changes: Save the new configuration with copy running-config startup-config.