When there are multiple matches, the router uses the longest prefix matching rule; that
is, it finds the longest matching entry in the table and forwards the packet to the link interface associated with the longest prefix match.
Given dest.address
131.23.151.76: 1 0 0 0 0 0 1 1 . 0 0 0 1 0 1 1 1 . 1 0 0 1 0 1 1 1 . 0 1 0 0 1 1 0 0
3 -- 131.16.0.0/ 12: 1 0 0 0 0 0 1 1 . 0 0 0 1 x x x x . x x x x x x x x . x x x x x x x x No.of prefix bits matched = 12
5 -- 131.28.0.0/ 14: 1 0 0 0 0 0 1 1 . 0 0 0 1 1 1 x x . x x x x x x x x . x x x x x x x x Bit mismatch(discarded) as highlighted
2 -- 131.19.0.0/ 16: 1 0 0 0 0 0 1 1 . 0 0 0 1 0 0 1 1 . x x x x x x x x . x x x x x x x x Bit mismatch(discarded) as highlighted
1 -- 131.22.0.0/ 15: 1 0 0 0 0 0 1 1 . 0 0 0 1 0 1 1 x . x x x x x x x x . x x x x x x x x No.of prefix bits matched = 15
Ans : Thus the identifier of the output interface on which this packet will be forwarded is 1.