An example of how TTL can be utilized is traceroute. It purposely sets the time to live to zero so an error is reported (TTL is exceeded) at each hop. The SA (Source Address) is read from each packet returned and reports this as a hop along with hop latency. Because each router acts as a “proxy” traceroute will get the message from each router (hop). This is a pretty cool example of how TTL can be used.