Cisco Updated 100-490 Exam Questions and Answers by chase

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

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.

References:

Cisco Networking Academy: Introduction to Networks Course

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.

The tftpdnld command in Cisco IOS is specifically designed for recovering or upgrading a system image. Here's how it's the most effective method:

Purpose: The tftpdnld command directly initiates a TFTP download of a new system image and stores it in memory. This is ideal for replacing a corrupt image or upgrading to a newer version of Cisco IOS.

ROMmon: The tftpdnld command can often be used from ROMmon mode, which is essential when the existing image is unusable.

Efficiency: It streamlines the image transfer process specifically using TFTP, which is commonly used for Cisco IOS images.

Why other options are less ideal:

USB storage: While some newer Cisco devices may allow direct loading of an IOS image from USB, this isn't universally supported and often requires specific boot commands.

FTP: FTP (File Transfer Protocol) can be used for file transfers, but it's not as commonly used as TFTP in the context of Cisco IOS image recovery. The tftpdnld command offers a more tailored solution for this purpose.

the xmodem command: XMODEM is a legacy file transfer protocol that is slower and less reliable than TFTP, especially for larger files like Cisco IOS images.