ARP Cache

What this ARP cache interview question tests

This is a straightforward technical question that probes your understanding of how network devices resolve IP addresses to physical (MAC) addresses in real time. It is the kind of question asked during networking-focused interviews at infrastructure and systems engineering roles, where candidates need to demonstrate solid grasp of foundational TCP/IP mechanics.

The question rewards clear, accurate knowledge of the Address Resolution Protocol and the data structures that support it. A strong answer identifies the key fields stored in a cache entry, explains why each is necessary, and may touch on cache behaviour such as timeout and entry invalidation. Interviewers often follow up by asking about cache poisoning, gratuitous ARP, or how entries are managed under high traffic.

• Layer 2 and Layer 3 address mapping
• Cache entry lifecycle and aging
• ARP request and reply mechanisms
• Broadcast domain constraints