Computer Networks/Tracert/Host

Tracert is a Windows command used to display the route (path) and transit delays of packets across an Internet Protocol (IP) network. These activities will show you how to use the tracert command to trace the route to a host.

Preparation

To prepare for this activity:

1. Start Windows.
2. Log in if necessary.

Activity 1 - Trace Route to the Default Gateway

To trace the route to the default gateway:

1. Open a command prompt.
2. Use ipconfig to display the default gateway address. Note the Default Gateway displayed.
3. Type tracert -d <default gateway address> where <default gateway address> is the default gateway address displayed above. For example, if the default gateway address was 192.168.1.1, you would type tracert -d 192.168.1.1. Then press Enter.
4. Observe the results. You should see one hop to the default gateway, because the default gateway is on the same network.

Activity 2 - Trace Route to an Internet Host without Name Resolution

8.8.8.8 is the IP address of one of Google's public DNS servers. To trace the route to this server:

1. Type tracert -d 8.8.8.8 and press Enter. The -d option disables host name resolution and therefore performs faster.
2. Observe the results. Identify the number of hops (routers) and time delay between your host and the Google server. Hops that show * and "Request timed out." are routers that are configured to not respond to Internet Control Message Protocol (ICMP) packets. These may sometimes be referred to as black hole routers.

Activity 3 - Trace Route to an Internet Host with Name Resolution

To trace the route to an Internet host with name resolution:

1. Type tracert 8.8.8.8 and press Enter. Note the removal of the -d option used above.
2. Observe the results.

Activity 4 - Terminate a Trace

To terminate a trace:

1. Type tracert 8.8.8.8 and press Enter.
2. During the trace, press Ctrl + C to terminate the command. Traces are frequently terminated early when the destination appears to be unreachable.
3. Close the command prompt to complete this activity.

Readings

• Wikipedia: traceroute
• Wikipedia: Google Public DNS
• Wikipedia: Black hole (networking)
• Wikipedia: Name resolution
• Wikipedia: Control-C

References

• Microsoft TechNet: Tracert