CN – Lab Exercise 2

Objective 

·   Learn to use the TCP/IP Packet Internet Groper (ping) command from a workstation.

·   Learn to use the Traceroute (tracert) command from a workstation.

·   Observe name resolution occurrences using WINS and/or DNS servers.

Background

This lab assumes the use of any version of Windows. This is a non-destructive lab and can be done on any machine without concern of changing the system configuration.  Ideally, this lab is performed in a LAN environment that connects to the Internet. It can be done from a single remote connection via a modem or DSL-type connection. The student will need the IP addresses that were recorded in the previous lab. The instructor might also furnish additional IP addresses.

Note: Ping has been used in many DOS attacks and many school network administrators have turned off ping, echo reply, from the border routers. If the network administrator has turned off echo reply then it is possible for a remote host to appear to be offline when the network is operational.

Step 1 Establish and verify connectivity to the Internet

This ensures the computer has an IP address.

Step 2 Access the command prompt

Use the Start menu to open the Command Prompt window. Press Start, type Run then type cmd which stands as Command Prompt

 

Step 3 ping the IP address of another computer

In the window, type ping, a space, and the IP address of a computer recorded in the previous lab. 

 

Ping uses the ICMP echo request and echo reply feature to test physical connectivity. Since ping reports on four attempts, it gives an indication of the reliability of the connection. Look over the results and verify that the ping was successful. Is the ping successful?

If not, perform appropriate troubleshooting. 

If a second networked computer is available, try to ping the IP address of the second machine.

Note the results.

Step 4 ping the IP address of the default gateway

 

Try to ping the IP address of the default gateway if one was listed in the last exercise. If the ping is successful, it means there is physical connectivity to the router on the local network and probably the rest of the world.

Step 5 ping the IP address of a DHCP or DNS servers

 

Try to ping the IP address of any DHCP and/or DNS servers listed in the last exercise. If this works for both server and they are not in the network, what does this indicate?

The result was a request time out which indicates thst no connection will be able to be established.

Was the ping successful?

No

If not, perform appropriate troubleshooting.

Step 6 ping the Loopback IP address of this computer

Type the following command: ping 127.0.0.1 

The 127.0.0.0 network is reserved for loopback testing. If the ping is successful, then TCP/IP is  properly installed and functioning on this computer.

Was the ping successful?

Yes

If not, perform appropriate troubleshooting.

Step 7 ping the hostname of another computer

Try to ping the hostname of the computer that was recorded in the previous lab. 

If the ping is successful, it means the computer was able to resolve the host name to an IP address. Without name resolution, the ping would have failed because TCP/IP only understands valid IP addresses, not names.

If the ping was successful, it means that connectivity and discovery of IP addresses can be done with only a hostname. In fact, this is how many early networks communicated. If successful, then ping a hostname also shows that there is probably a WINS server working on the network. WINS servers or a local “lmhosts” file resolve computer host names to IP addresses. If the ping fails, then chances are there is no NetBIOS name to IP addresses resolution running.

Note: It would not be uncommon for a Windows Vista or 7 networks to not support this feature.

It is an old technology and often unnecessary.

If the last ping worked, try to ping the hostname of any another computer on the local network.

Note: The name had to be typed in quotes because the command language did not like the  space in the name. 

Step 8 ping the Google web site

Type the following command: ping www.google.com

The first output line shows the Fully Qualified Domain Name (FQDN) followed by the IP address. A

Domain Name Service (DNS) server somewhere in the network was able to resolve the name to an IP address. DNS servers resolve domain names, not hostnames, to IP addresses. 

Without this name resolution, the ping would have failed because TCP/IP only understands valid IP addresses. It would not be possible to use the web browser without this name resolution.

With DNS, connectivity to computers on the Internet can be verified using a familiar web address, or domain name, without having to know the actual IP address. If the nearest DNS server does not know the IP address, the server asks a DNS server higher in the Internet structure

Step 9 ping the Microsoft web site

Type the following command: ping www.microsoft.com

Step 10 Trace the route to the Yahoo web site

Type tracert www.yahoo.com and press Enter.

Explain tracert and differentiate it with ping.

Traceroute is a utility that records the route (the specific gateway computers at each hop) through the Internet between your computer and a specified destination computer. It also calculates and displays the amount of time each hop took. Traceroute is a handy tool both for understanding where problems are in the Internet network and for getting a detailed sense of the Internet itself. Another utility, PING, is often used prior to using traceroute to see whether a host is present on the network.

Step 11 Trace other IP addresses or domain names

Try tracert on other domain names or IP addresses and record the results. An example is

tracert www.msn.de.  

Step 12 Trace a local host name or IP address

Try using the tracert command with a local host name or IP address. It should not take long because the trace does not pass through any routers.

Reflection 

If the above steps are successful and ping or tracert can verify connectivity with an Internet Web site, what does this indicate about the computer configuration and about routers between the computer and the web site? What, if anything, is the default gateway doing?