From LQWiki
Traceroute is a program for determining the path that packets take to reach another Internet host. It works by sending packets with short time-to-live (TTL) values, and seeing which hosts send back error messages. For example, a packet with a TTL of 1 will die at the first host along the route, and that host (if it is standards-compliant) will transmit an error packet back.
Traceroute is useful for debugging networking problems. If you aren't sure why you can't reach a particular computer, use traceroute and see where packet traffic stops, or starts to show high round-trip times.
This page is available under a