IP route lookup :Longest match routing

10.0.0.0/8 ? R3

10.1.0.0/16 ? R4

20.0.0.0/8 ? R5

0.0.0.0/0 ? R1

R2’s IP forwarding table

R2

R3

R4

Most of 10.0.0.0/8 except for

10.1.0.0/16

10.1.0.0/16

Based on destination IP address

Packet: Destination

IP address: 10.1.1.1

10.1.1.1 & 00.00.00.00

vs.

0.0.0.0 & 00.00.00.00

Match! (length 0)

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