Trace
The trace command is similar to the ping command, except that the replies are requested at each hop along the way to the destination.
Trace sends multiple ICMP packets with progressively higher time-to-live counters (TTL) until the packet reaches the destination.
If there are three routers between the destination and the source of the trace, there will be four replies to the message; one for each hop along the way and one when the trace reaches the final destination.
The trace command is especially useful for determining where in the process the communication is breaking down.