Wrong Mask, No Reply

Lesson 10 of 35 in Coddy's LAN Labs course.

Every host judges "are we neighbors?" with its own mask. That creates a classic one-way failure: pc1 with /24 thinks pc2 is next door and sends the request; pc2 with /25 looks at pc1's address, decides it is a different network, and has no gateway to send the reply to. The request arrives; the reply never leaves.

netlab reports this as no reply rather than unreachable, and says exactly what the far side thinks. A mask typo on one machine is among the most common real-world LAN faults, and this message is what it looks like.

Challenge

Easy

pc1 is 192.168.1.10/24, pc2 was mistakenly set to 192.168.1.200/25. Ping pc2 from pc1 and read the message, fix pc2's mask (keep the address, use /24), then ping again.

Expected output:

pc1 -> pc2: no reply (pc2 thinks 192.168.1.10 is on a different subnet and has no gateway)
pc2 eth0: 192.168.1.200/24 (mask 255.255.255.0, network 192.168.1.0/24)
pc1 -> pc2: reply from 192.168.1.200 (ttl=64)

Try it yourself

Terminal