Tracert is a TCP/IP utility which allows the user to determine the route packets take to reach a particular host. Trace route works by increasing the "time to live" value of each successive packet sent.
The first packet has a TTL value of one, the second two, and so on. When a packet passes through a host, the host decrements the TTL value by one and forwards the packet to the next host. When a packet with a TTL of one reaches a host, the host discards the packet and sends an ICMP time exceeded.
Clients are sometimes asked to perform this function to determine if there is a break in communications between themselves and a remote server such as our servers.