Some of the important commands useful in trouble shooting TCP/IP networks are:
NBTSTAT : This utility displays current NetBIOS over TCP/IP connections, and display NetBIOS name cache. Netstat displays active TCP connections, ports on which the computer is listening, Ethernet statistics, the IP routing table, IPv4 statistics, and IPv6 statistics. Used without parameters, netstat displays active TCP connections. NETSTAT is used to review all inbound / outbound TCP/IP connection. Nbtstat is designed to help troubleshoot NetBIOS name resolution problems. When a network is functioning normally, NetBIOS over TCP/IP (NetBT) resolves NetBIOS names to IP addresses. The nbtstat command removes and corrects preloaded entries using a number of case-sensitive switches.
NETSTAT: netstat stands for network statistics. This command displays incoming and outgoing network connections as well as other network information. Displays protocol statistics and current TCP/IP connections since the server was last booted.
TRACERT: Used to determine which route a packet takes to reach its destination from source. IPCONFIG Used to display Windows IP configuration information. TRACERT command can be used to determine the path that a packet takes while traversing on the network before reaching the destination.
NSLOOKUP: This utility enables users to interact with a DNS server and display resource records. The nslookup command will look up the IP addresses associated with a domain name.
nslookup also allows you to perform a reverse lookup to find the domain name associated with an IP address. Displays information that you can use to diagnose Domain Name System (DNS) infrastructure. The Nslookup command-line tool is available only if you have installed the TCP/IP protocol.
ROUTE: Used to display and edit static routing tables. Displays and manipulates route information.