Tracing Packets over the Internet
Tracing Packets over the Internet
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Packets of information don't usually go directly from one computer to another computer over the Internet. Instead, they are involved in a huge game of "whisper-down-the-lane," in which packets are passed from computer to computer until they reach their destination. If your data seems to be moving slowly, you can use the Tracert (short for trace route) program to follow your packets across the Internet, from your computer to an Internet host you frequently use. The technique Tracert uses doesn't always work, so it's quite possible running Tracert to a remote computer can fail, even though the computer is working and accessible.
To run Tracert, open a Command Prompt window by choosing Start | All Programs | Accessories | Command Prompt. Then type the Tracert command:
tracert system
Replace system with either the numeric IP address or the Internet name of the computer to which you want to trace the route. Then press ENTER.
tip To see a listing of all the command-line options for the Tracert program, type tracert at the DOS prompt, with no system address.
For example, you can trace the route of packets from your computer to the Internet Gurus Web directory at net.gurus.com by typing:
tracert net.gurus.com
You see a listing like this:
Tracing route to net.gurus.com [208.31.42.79]
over a maximum of 30 hops:
1 * * * Request timed out.
2 148 ms 149 ms 139 ms rtr.shoreham.net [208.144.253.1]
3 149 ms 149 ms 149 ms shoreham253.greenmountainaccess.net [208.144.253.253]
4 149 ms 139 ms 149 ms richmond-1.greenmountainaccess.net [208.144.252.13]
5 190 ms 179 ms 189 ms sl-gw20-nyc-6-1-0-TS8.sprintlink.net [160.81.215.241]
6 216 ms 189 ms 229 ms sl-finlak-7-0.sprintlink.net [160.81.228.18]
7 220 ms 199 ms 219 ms 208.31.47.5
8 229 ms 199 ms 209 ms net.gurus.com [208.31.42.79]
Trace complete.
The listing shows the route the packets took from your computer to the specified host (sometimes Tracert reports a different host name from the one you specified, which means the host has more than one name). For each hop (stage of the route), Tracert sends out three packets and reports the time each packet took to reach that far. It also reports the name and numeric IP address of the host.
Table shows the options you can use with the Tracert program (type them before the host name or address). A few other arcane options are not listed here.
Option Description
-d Specifies not to resolve addresses to host names, so the resulting list of hosts consists only of numeric IP addresses
-h n Specifies a maximum number of n hops to trace before giving up
-w n Specifies that the program wait n milliseconds for each reply before giving up
Table 3: Options for the Tracert Program
