3. In the given Linux command to view the ARP cache ($ ip -4 neigh), what does each field represent, and why is it important for a network administrator to monitor the status of entries such as "REACHABLE" and "STALE"?
This question tests the candidate's familiarity with the Linux command for ARP cache inspection and their ability to interpret the output. It also assesses their awareness of the importance of monitoring entry statuses for network maintenance.
The command ip -4 neigh consists of IP, and hardware addresses for the hosts that the kernel knows about. The last field indicates the status of the entry in the cache. REACHABLE means that some communication with the host occurred recently, and STALE means that its been a while and the entry should be refreshed.
