traceroute

traceroute is a command which is used to trace the route of a packet through a TCP/IP network.

traceroute is a Unix command. Under Microsoft Windows, the traceroute command has been renamed `tracert`. Unix `traceroute` and Microsoft Windows `tracert` are designed to accomplish the same task, but differ in the way they display output, in the way they send test packets, and in the number of command line options they provide.

Sample `tracert` output

This is the result of tracing the network route to www.mit.edu:

C:\>tracert www.mit.edu

Tracing route to www.mit.edu [18.7.22.83] over a maximum of 30 hops:

1 2 ms 4 ms 2 ms 192.168.1.1
2 * * * Request timed out.
3 10 ms 50 ms 11 ms 68.86.105.109
4 28 ms 9 ms 9 ms 68.86.103.45
5 10 ms 10 ms 11 ms 68.86.103.182
6 53 ms 29 ms 10 ms 12.124.157.53
7 53 ms 45 ms 60 ms gbr1-p40.dvmco.att.net [12.123.36.146]
8 88 ms 47 ms 36 ms gbr1-p60.la2ca.att.net [12.122.1.29]
9 72 ms 34 ms 39 ms tbr2-p013301.sffca.att.net [12.122.12.133]
10 37 ms 33 ms 79 ms 12.122.80.57
11 35 ms 35 ms 35 ms so-8-1.car3.Level3.net [209.0.227.29]
12 36 ms 44 ms 36 ms ae-1-51.bbr1.Level3.net [4.68.123.1]
13 93 ms 87 ms 83 ms so-2-0-0.mp2.Level3.net [64.159.4.181]
14 91 ms 84 ms 115 ms ge-1-1-55.car2.Level3.net [4.68.100.131]
15 126 ms 84 ms 90 ms 4.79.2.2
16 95 ms 96 ms 95 ms W92-RTR-1.MIT.EDU [18.168.0.25]
17 96 ms 100 ms 95 ms WWW.MIT.EDU [18.7.22.83]

Trace complete.

From this output, we can see that our packets took 17 network layer hops to reach their destination.

We can see that our packets traversed both the AT&T and Level3 networks along the way.

We can also see the times the first, second, and third test packets took to cross each of the network hops.

In addition, we can see that the 2nd hop didn't respond to our request within 5 seconds. Because of this, we don't know the IP address of that network device.