Which of the following descriptions about router forwarding data are correct? (Multiple choice)

Question

Options

• AIf the next hop of the route in the queried table entry is not directly connected, route selection will be performed.
• BThe router will determine the next hop and outgoing interface based on the entries in the FIB forwarding table.
• CThe router will determine the next hop and outbound interface based on the entries in the local route routing table.
• DThe router will determine the next hop and outgoing interface based on the entries in the protocol routing table.

• A
  79% (33)
• C
  14% (6)
• D
  7% (3)

Explanation

A is correct because when a routing table entry points to a next hop that isn't directly connected, the router must perform a recursive lookup - it re-queries the FIB to resolve the actual reachable next hop and outgoing interface. This "route selection" step chains lookups until a directly connected interface is found.

B is correct because routers perform packet forwarding using the FIB (Forwarding Information Base), which is a hardware-optimized table derived from the best routes in the RIB. The FIB is what the data plane actually queries - it already stores resolved next-hop and interface information for fast lookup.

C is wrong because "local routes" (host routes pointing to the router's own IP addresses) indicate packets destined for the router itself, not routes used to forward transit traffic to other destinations.

D is wrong because the "protocol routing table" (RIB/routing protocol table) is a control-plane structure that holds raw routes from protocols like OSPF or BGP. It feeds the FIB but is not directly used for forwarding decisions - the FIB is.

Memory tip: Think "F in FIB = Forwarding" - the FIB is the only table the router's data plane touches when forwarding packets. Everything else (RIB, protocol tables) is control-plane input that builds the FIB, not the forwarding mechanism itself.

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