Cisco 100-490 Practice Test - Questions Answers, Page 4

Thedata link layerof the OSI model, which is Layer 2, defines how data is formatted for transmission and controls access to the physical media. This layer is responsible for the node-to-node delivery of data and handles error detection and correction from the physical layer. It also manages the way data packets are sent over the network, including the framing, addressing, and flow control.The data link layer ensures that messages are delivered to the proper device on a LAN using hardware addresses (MAC addresses) and translates messages from the network layer into bits for the physical layer to transmit

Topic 2, Cisco Equipment and Related Hardware

The show environment command in Cisco devices is used to display the status of the system's environment, including power supplies and sensor temperatures. This command provides a comprehensive overview of the environmental conditions affecting the device, such as temperature readings and power supply status.

Option A, show hardware, is not specific to power supplies and sensor temperatures. Option B, show module, displays information about the network modules installed in the device but not the environmental conditions. Option D, show diag, is used for diagnostic purposes and does not specifically provide the status of power supplies and sensor temperatures.

Therefore, the correct answer is C, show environment, which is the command that specifically shows the status of power supplies and sensor temperatures in Cisco devices12.

Cisco Community discussions on power supply details1.

Cisco documentation on Environmental Monitoring and Power Management2.

Two standard fiber-optic connectors are Lucent Connectors (LC) and Subscriber Connectors (SC). The Lucent Connector, commonly referred to as LC, was developed by Lucent Technologies and is characterized by its small form factor with a 1.25mm ferrule. It is widely used in high-density applications due to its compact size and square shape1. The Subscriber Connector, or SC, is known for its push-pull latching mechanism and uses a 2.5mm ferrule. It is a square-shaped, duplex connector that has been a dominant fiber optic connector for decades due to its performance and reliability12.

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.