Networking 101

Copyright Priscilla Oppenheimer

Lab 2 Testing Network Configuration

Objectives

• Learn tools for discovering a computer's network configuration with the Windows or Linux operating systems
• Compare the network information that you gather to that of other PCs on the network
• Test the reachability of other computers
• Test the throughput when downloading a large file to your compute

Step 1. Gather TCP/IP configuration information.

1. On Windows open a Command Prompt window.
1. Select Run from the Start menu and type cmd and Enter.
2. Type ipconfig/all and Enter. The spelling is critical, but the case is not.
2. On Linux, start a console session.
1. From the taskbar, click on the Console icon (looks like a terminal and a shell).
2. Type ifconfig and Enter. The spelling and case are critical. Notice that the spelling is different from the Windows spelling.
3. Some other Linux commands that are helpful for checking your configuration:
1. route
2. hostname
3. cat /etc/resolv.conf
3. Record the following TCP/IP information for this computer.
1. IP address ____________________________________________________
2. Subnet mask __________________________________________________
3. Default gateway _______________________________________________

Step 2. Compare this computer's TCP/IP configuration to that of others on the network.

1. Record a couple other IP addresses ________________________________________
2. What is similar about these IP addresses and your own address? _____________________________________________________________________
3. What is similar about the default gateways? _____________________________________________________________________

Step 3. Check additional TCP/IP configuration information.

1. What is this computer's host name? ________________________________________
2. Which computer(s) are providing naming services for this host? In other words, which computer(s) are acting as a Domain Name System (DNS) server? _____________________________________________________________________
3. What is the physical address (Ethernet HWaddr) of this computer? _______________
4. What, if any, similarities do you see in this computer's physical address and other computers' physical addresses? ___________________________________________

Step 4. Ping the IP address of another computer.

1. In the command prompt window, type ping, a space, and the IP address of another computer in the lab. Was the ping successful? _______________________________

Ping uses the Internet Control Message Protocol (ICMP) echo message to test the reachability of another computer. It makes multiple attempts and records the number of bytes returned and the time it took to receive a reply.

2. Ping the address of the default gateway. Was the ping successful? ____________________
3. If you can reach the default gateway, then you can hopefully reach other networks. Try to ping a computer not on your own network. Was the ping successful? ____________________
4. Try to ping the DNS server. Was the ping successful? _________________________ If you can reach the DNS server, then you can hopefully reach another computer by name.
5. Try to ping www.yahoo.com. Was the ping successful? ____________________
6. Ping a few other websites, such as www.cisco.com and www.microsoft.com and record the results. __________________________________________________________________________________________

Step 5. Ping yourself.

1. Sometimes when troubleshooting, it helps to know if you can even reach yourself! Try to ping your own computer by its IP address. Was the ping successful? ________________
2. Now, try pinging the loopback IP address. Type ping 127.0.0.1. Was the ping successful? _______________________

Step 6. Trace the route to a website.

1. Type tracert www.cisco.com and press Enter. (On Linux the command is traceroute). Tracert (or traceroute) shows each router that your message goes through on its route to the destination. Each router represents a point where one network connects to another network and the packet was forwarded through. Note that your computer contacted each router three times, so that you have three timing results in milliseconds (ms) for each router.
2. Trace an IP address or name for a host in Europe, for example, www.msn.de. How many routers did your message go through? _______________________________________________
3. Trace an IP address or name for a host in Ashland, for example, www.ashlandfn.org. How many routers did your message go through? _______________________________________________

Step 7. Test your throughput when downloading a large file.

1. There are many ways to test your throughput and you may use any method you wish, but here is one way to do it:
2. Start a Web browser from the desktop.
3. Go to http://noc.ashlandfiber.net/ and download the 10 MB test file. If it's excruciatingly slow on the lab network, don't worry about downloading the entire file. You can still get a measurement without downloading the entire file.
4. Record your throughput:
1. in Kilobytes (KB) per second (KB/sec)_______________
2. in Kilobits (Kb) per second (Kbps)__________________

Reflection

If you can't ping or tracert to an Internet website, which commands would you use to verify that your own configuration is correct? What other troubleshooting might you do?

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