Forwarding uses the longest-prefix-match algorithm. 192.168.1.129 belongs to the 192.168.1.128/25 network.

In the shown routing table the entry for 192.168.1.128/25 lists next-hop 10.126.131.250, which therefore becomes the gateway chosen for packets destined to 192.168.1.129.

A. 10.126.131.251 – Appears in the table for a broader prefix; superseded by the more specific /25 route.

B. 10.126.131.252 – Also associated with a less-specific network; not selected under longest-prefix rules.

D. 10.126.131.248 – Either default route or another summary; overridden by the /25 entry.

1. RFC 1812

“Requirements for IP Routers”

§5.2.4 (Route Lookup) – explains longest-prefix selection.

2. Kurose & Ross

Computer Networking 8th ed.

Ch.4 p.301 – forwarding decision based on most-specific prefix.

3. MIT OCW 6.829 “Network and Computer Security”

Lecture 3 notes

slide 14 – longest-prefix match example.

4. Ericsson ECP-206 Student Guide

Module 3 “IP Forwarding”

p.3-15 – routing-table search order and next-hop determination.