Cisco Certified Network Professional 2025 – 400 Free Practice Questions to Pass the Exam

The command "show ip cef adjacency glean" is specifically designed to help diagnose ARP-related issues in a Cisco network that utilizes Cisco Express Forwarding (CEF). When you run this command, it displays information about how CEF is handling adjacencies for Layer 2 and Layer 3 packets, and highlights any entries in the adjacency table that might not have a corresponding ARP entry.

Using this command is critical in understanding how CEF is managing ARP operations, particularly when there are potential problems, such as dropped packets due to missing MAC addresses in the ARP table. It gives a real-time overview of how adjacencies are established, which can be key to troubleshooting connectivity issues that arise from ARP discrepancies.

In contrast, other options like "show ip arp" and "show arp status" focus on displaying the ARP table and overall ARP status, but they do not delve specifically into how ARP interacts with CEF's adjacency management. While they provide valuable ARP information, they are not tailored for monitoring ARP issues within the context of CEF. The "show cef arp" command is also less specific to adjacency issues; it offers a view of ARP as it relates to CEF but does not provide