Network tracing tools for the TCP/IP layer include:
netstat – displays current TCP/IP network connections and protocol statistics.
TDImon – an application that lets you monitor TCP and UDP (User Datagram Protocol) activity, track network-related configuration problems, and analyze application network usage. This tool is available at the Sysinternals Web site.
ping – attempts to elicit a response from a specified host.
traceroute – helps you determine the route IP packets take to a network host.