Cisco 100-490 Dumps

While the initial answers focused on the most common causes, here's why the other options could also contribute to an interface being stuck in the "up/down" state:

A. Speed or Duplex Mismatch: Devices on either end of an Ethernet connection need to use compatible speed (e.g., 100 Mbps, 1 Gbps) and duplex (full-duplex or half-duplex) settings. Mismatches can prevent the line protocol from coming up even if the physical link is established.

B. Layer 2 Mismatch in Encapsulation Type: Some protocols used on Ethernet networks, like ISL and 802.1Q, have specific encapsulation requirements. If devices on each end aren't using the same encapsulation type, the line protocol will likely remain down.

C. The Ethernet Interface Has Been Manually Disabled: Correct! Administrators can put an interface in a shutdown state using commands like shutdown. This brings down the line protocol even if the physical connection is good.

D. Keepalives Are Not Being Received by the Local Device: While less likely to be the sole cause, issues with keepalive mechanisms used in some routing protocols could potentially lead to the line protocol going down. If the local device expects keepalives and doesn't receive them, it might assume a connectivity problem and affect the interface status.

E. The Ethernet Cable Might Not Be Attached Properly: While a disconnected or faulty cable would usually make the interface down/down, it's possible in some scenarios for a partially connected or damaged cable to result in a link being detected (Layer 1 up) but with errors preventing the line protocol (Layer 2) from initializing.

Troubleshooting network issues often involves considering multiple factors and testing different possibilities. The "up/down" status gives important clues but might have several potential root causes.

The copy startup-config running-config command is used during the password recovery process on a Cisco router to load the saved configuration into the device's active running configuration. Here's why this is the correct choice:

Password Recovery Context: Password recovery often involves booting into ROMmon mode and changing the configuration register to bypass the normal boot process. This leaves the device with a blank running configuration.

Restoring Configuration: The copy startup-config running-config command copies the stored configuration (startup-config) from NVRAM into the running-config, which is used by the router for its operations.

Why other options are incorrect:

load_helper: While the load_helper command sometimes appears in password recovery procedures, it's typically used for older models and may not be necessary for all Cisco routers.

configure terminal: This command simply enters global configuration mode. It doesn't directly load a configuration.

copy running-config startup-config: This command saves the active running configuration into NVRAM as the startup-config. It's the reverse of what you need for password recovery.

DRAM, or Dynamic Random-Access Memory, is the type of memory that is erased when a Cisco device is rebooted. DRAM is used to store the running configuration and routing tables of the device. Since DRAM is volatile memory, its contents are lost when the device is powered down or restarted. This is in contrast to non-volatile memory types like flash and NVRAM, which retain their contents even after a reboot1. References := Types of memory on a Cisco device - Study-CCNA