Which data structure does a router consult to decide where to forward a packet?

• A. Routing table
• B. ARP table
• C. MAC address table
• D. DNS records

Answer: (A)

A router decides where to forward a packet by consulting its routing table. This table lists destination networks or prefixes and the next-hop address (or exit interface) to reach each one. When a packet arrives, the router looks at the destination IP and performs a longest-prefix match against the routing table to find the best route. The chosen entry tells it which interface to use and the next-hop address to forward the packet toward.

After the next-hop is determined, the router uses the ARP table to map that next-hop IP to a local MAC address so the frame can be delivered on the next hop. The MAC address table is used by switches to forward frames within a LAN, not for the router’s route decision. DNS records map domain names to IP addresses, which is a prior resolution step, not how the router decides the path to a destination.