IP subnetting (two /26 subnets)

Objective

Split 10.0.0.0/24 into two /26 subnets joined by a router: hosts in one subnet talk directly, hosts in the other need the router.

Procedure

1. Run: A → B stays inside 10.0.0.0/26 (no router hop); A → C crosses R1 (two extra hops, TTL 63).
2. Change C's mask to /24 and run again: C no longer sees the subnet split and the ping fails.

Theory

A /26 mask leaves 6 host bits: 62 hosts per subnet (10.0.0.0–63 and 10.0.0.64–127). A host compares the destination with its own network: inside the subnet it ARPs for the destination, outside it sends to the default gateway.

Network blocks used

3 × Host / PC, Router, 2 × Switch

More Computer Networks Lab experiments

• Static routing across three routers
• Traceroute: discovering the path with TTL
• TTL expiry and ICMP time-exceeded
• RTT and packet loss on a lossy link
• Packet size versus latency