Solution overview
In this lab you take over a Linux workstation that cannot reach the network, even though the network itself is healthy. Four separate faults are waiting for you: a subnet prefix that is too narrow, a missing default route, a stale hosts-file entry, and a firewall on the far server that quietly drops the one port the application needs. Each fault produces the same vague symptom, so guessing gets you nowhere. You work through the layers in order with the tools this module's videos taught: the ip suite to check addressing and routing, dig and the name-versus-IP split test to isolate DNS, then ss and tcpdump together to show whether a failed connection belongs to the path or to the host at the other end. Every fix is made live, proven with a retest, and then made permanent.