Network troubleshooting commands are essential command-line utilities that diagnose connectivity issues, analyze traffic patterns, and verify network configurations across Layer 2 through Layer 7 of the OSI model. These tools range from basic reachability tests like ping and traceroute to advanced packet capture with tcpdump and comprehensive port scanning with nmap. The key insight: effective troubleshooting moves systematically through the network stack — test physical connectivity first, then routing, then DNS, then application-level protocols — and the right tool at each layer saves hours of guesswork.