What is the difference between routing and switching?
Assesses fundamental understanding of Computer Networks conventions, runtime behavior, and memory/performance considerations.
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
Switching and routing both forward packets, but at different layers and scopes.
A switch works at layer 2 using MAC addresses within a single broadcast domain, the LAN. It learns which MAC is reachable on which port by inspecting source addresses and forwards frames only to the correct port, flooding unknown destinations. VLANs segment one physical switch into logical LANs.
A router works at layer 3 using IP addresses and moves packets between networks. It consults a routing table built from directly connected networks, static routes and dynamic protocols such as OSPF, EIGRP or BGP, and picks the longest matching prefix. It also decrements the TTL and can perform NAT.
host -> switch (MAC) -> router (IP) -> internet
Routers break broadcast domains and connect dissimilar networks; switches are faster and cheaper but confined to the local segment. Layer 3 switches combine both functions.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.