A trace returns a list of hops as a packet is routed through a network. The form of the command depends on where the command is issued. When performing the trace from a Windows computer, use tracert. When performing the trace from a router CLI, use traceroute, as shown in Figure 1.

Like ping commands, trace commands are entered in the command line and take an IP address as the argument.

Assuming that the command will be issued from a Windows computer, we use the tracert form:

C:\> tracert

Tracing route to over a maximum of 30 hops

1 2 ms 2 ms 2 ms

2 * * * Request timed out.

3 * * * Request timed out.

4 ^C

The only successful response was from the gateway on Router A. Trace requests to the next hop timed out, meaning that the next hop router did not respond. The trace results indicate that the failure is therefore in the internetwork beyond the LAN.

Capturing the traceroute output can also be done from the router prompt, as shown in Figure 2.