Traceroute is an application that traces the path data takes from one computer to another. Basically, a traceroute is a map that shows what stops or locations that data must pass through in order to go from one computer to another.
To be an effective troubleshooting tool, the traceroute needs to be run from a computer experiencing the problem while the problem is occurring.
To Run a Traceroute in Windows
The command application (cmd.exe) is used to run a traceroute on Windows. Launching it is slightly different depending on your version of Windows:
- In Windows 7:
- click on the Start menu
- type “cmd” and press Enter to get a command prompt.
- In Windows 8 & Windows 10,
- Type “command” into the search menu and press Enter for a command prompt.
- move your mouse to the bottom-left corner of the screen to bring up the Start icon.
- Right-click on Start and select Run.
- Then type “command” and press Enter to launch the application.
- Alternatively, you can type “command” into the Search field in the Charms menu after moving your mouse to the lower right corner of your desktop.
To run the traceroute, type into the command prompt, where “domainname.com” is the name of the server to which you are having difficulty connecting.
The traceroute may take only a few seconds or a few minutes. Typically, the closer you are to the server, geographically, the more quickly the traceroute will complete.
To Run a Traceroute in Mac OS X
If you have a Mac, you can use the built-in network tools to run a traceroute.
- Launch Spotlight (with ⌘ + SPACE or by clicking on the magnifying glass in your menu) to search for and launch Network Utility.
- Select the Traceroute tab and enter the hostname or domain name.
- You also can perform a traceroute from the Terminal app.
To Run a Traceroute in Linux
At the command line, type:
What Does the Traceroute Show You?
Let’s take a few samples of traceroute outputs.
The output from that command shows a successful trace:
traceroute to msu.edu (220.127.116.11), 30 hops max, 40 byte packets
1 lw-dc2-hsrp-vlan132.rtr.liquidweb.com (18.104.22.168) 1.330 ms 1.420 ms 1.554 ms
2 lw-dc2-core4-po2.rtr.liquidweb.com (22.214.171.124) 1.092 ms 1.311 ms 1.451 ms
3 lw-dc1-core1-ge3-5.rtr.liquidweb.com (126.96.36.199) 1.596 ms 1.897 ms 2.209 ms
4 lw-dc1-border3-ge4.rtr.liquidweb.com (188.8.131.52) 1.657 ms 1.748 ms 1.894 ms
5 184.108.40.206 (220.127.116.11) 4.748 ms 5.382 ms 5.453 ms
6 cr81.dtrmi.ip.att.net (18.104.22.168) 12.893 ms 12.035 ms 11.043 ms
7 cr1.cgcil.ip.att.net (22.214.171.124) 11.509 ms 11.615 ms 11.769 ms
8 126.96.36.199 (188.8.131.52) 10.645 ms 10.711 ms 10.760 ms
9 184.108.40.206 (220.127.116.11) 9.473 ms 9.537 ms 9.605 ms
10 xe-0-0-0x14.msu6.mich.net (18.104.22.168) 15.047 ms 14.458 ms 14.487 ms
11 22.214.171.124 (126.96.36.199) 16.976 ms 20.066 ms 20.137 ms
12 cc-t1-ge1-23.net.msu.edu (188.8.131.52) 20.228 ms 20.432 ms 20.312 ms
13 www.msu.edu (184.108.40.206) 16.856 ms 17.071 ms 16.341 ms
It looks like gibberish, right? But it’s actually fairly easy to understand. After the traceroute command, the program tells you what it’s doing:
- It has looked up the domain msu.edu
- It found msu.edu on the IP address of 220.127.116.11
- It now will attempt to find its way there using no more than 30 “hops” (stops along the way, or connections to routers), and it will send a packet of 40 bytes.
The numbers at the far left are the number of the hop, followed by the name and/or IP address of the router that hop is going through. You can see that this trace started within the Liquid Web network, progressed through AT&T and found its way to msu.edu.
The set of three numbers on the right side of the lines indicate the amount of time, in milliseconds, it took for that hop to complete. Traceroute performs each hop three times.