What is network troubleshooting and common tools?

Network troubleshooting is the systematic process of diagnosing and resolving network problems. Common tools: ping (test connectivity and measure latency), traceroute/tracert (trace the path and identify where packets are being dropped), nslookup/dig (query DNS records), ipconfig/ifconfig/ip addr (view IP configuration), netstat/ss (show active connections and listening ports), nmap (network scanning, open port discovery), Wireshark (packet capture and deep analysis), mtr (combines ping and traceroute), tcpdump (command-line packet capture). Systematic approach: work through the OSI model from bottom to top — verify physical connectivity first, then check IP configuration, default gateway, DNS, and finally application-level issues. Document problems and solutions for future reference.