Download TROUBLESHOOTING TCP/IP CONNECTIONS

Name -------------------------------------------Roll.No. ----------------------------------------Date----------------------------------------------Lab 9. Troubleshooting TCP/IP Connections
ARP
There are a number of TCP/IP utilities that can help you troubleshoot your connection on
a network. In Windows XP ipconfig will give you the network configuration
information. Here are three utilities that can help you troubleshoot your connection on a
network:
1. PING troubleshoots your network connection
2. ARP (address resolution protocol) helps you determine the hardware address
associated with a particular IP address.
3. TRACERT looks up the path your message takes, one IP address at a time.
Telnet is another utility that can help you troubleshoot your connection. We will work
with telnet in semester 2.
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ADDRESS RESOLUTION PROTOCOL (ARP)
ARP is a TCP/IP utility. It identifies the physical address of a computer based on a
known IP address. It also keeps a cache of such addresses. Here are some examples how
to use this utility:

Arp –a: displays current entries in arp cache

Arp –a 172.30.1.1: looks for the physical address of the computer with the
specified IP address.

Arp –d 172.30.1.1 deletes the entry for the specified IP address from the arp
cache.
To find out more about the arp command, type arp /? At the DOS prompt. Also, arp gets
its information from cache. There have be entries in the arp cache in order for you to see
something. Pinging another IP address will make an entry in the arp cache.
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PACKET INTERNET GROPER (PING)
The ping Utility
Ping is used to query a TCP/IP device to determine if a working connection
between hosts exists. Some say PING is short for Short for Packet INternet
Groper, ping sends out an Internet Control Message Protocol (ICMP) echo
request to a destination IP address. Under normal circumstances, a host that
receives the echo request will send back an “echo reply” immediately.
Most TCP/IP hosts have a ping utility; and all TCP/IP hosts can respond to ping
requests. Windows’ ping.exe sends four 32-byte echo requests by default.
Usually, ping parameters can be adjusted. It’s not uncommon for a network
administrator to run a series of 100 pings, or send very large pings to test a
network. Note that ping.exe outputs useful statistics, such as roundtrip times.
The PING command allows you to check your connections on the network/Internet. Use
the following commands in order when “pinging”. If there is no success pinging another
machine, check the cable, the link lights and the IP configuration.

PING 127.0.0.1: the IP address 127.0.0.1 is referred to as the loopback address.
If pinging the loopback address is successful, TCP/IP is installed and configured
correctly. Pinging your own interface is often the first step in isolating a TCP/IP
network problems. How do you know if the ping is successful? If you get a
“Reply from….”, similar to the following:
Pinging 172.29.2.1 with 32 bytes of data:
Reply from 172.29.2.1: bytes=32 time<10ms TTL=128
Reply from 172.29.2.1: bytes=32 time<10ms TTL=128
Reply from 172.29.2.1: bytes=32 time<10ms TTL=128
Reply from 172.29.2.1: bytes=32 time<10ms TTL=128
Ping statistics for 172.29.2.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

PING your computer IP address Remember how to find your own IP address?
IPCONFIG
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
PING your computer name : this command is identical to pinging your own IP
address. If this is not working, there might be a problem with your WINS server.

PING some IP address: This command allows you to ping any valid IP address
on your network o the Internet if you are connected.
TRACERT
Information between networks travels through routers. Tracert allows you to determine
the route your packet takes over the Internet. Use tracert if your messages cannot reach
the destination to determine where the problem is located. Here is a web site that allows
you to trace different routes: http://www.traceroute.org/
PROJECT 1 PING
1. Start a MS_DOS prompt.
2. Ping your loopback address. Did it work?
3. Find and record the IP address of your computer and the DNS server
Your I address:
DNS server address:
4. Ping your own IP address. Was the ping successful?
If a ping command is not successful, what do you need to check?
5. Ping your DNS server. Was the ping successful?
6. Find a partner and exchange each other’s computer names (NetBios names).
7. Ping your partner’s computer using the computer name. Was the ping successful?
How do you know that the ping was successful?
8. Ping yahoo.com. What is the IP address for yahoo?
PROJECT 2 TRACERT:
1. Use tracert Microsoft.com. Record the response you get.
2. Use tracert pengo.cabrillo.cc.ca.us. Record the response.
3. Use tracert yahoo.com. Record the response.
4. Use tracert to trace the route to your partner’s computer. Record the response.
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5. Use your responses to answer the following questions:
What are hops?
How many hops are allowed with the tracert command?
What happens when you try to trace the route to Microsoft.com and yahoo.com?
What is your DNS’s server IP address?
What is the name of your DNS server?
At what layer of the TCP/IP model do ping and tracert operate?
You can take screen shots to record your results. Remember to reverse the colors in
the DOS window to save ink.
PROJECT 3 ARP:
1. Use the arp request to find the physical address of your partner’s computer or any
other computer in the lab room. Record the IP address, the MAC address and the
NetBios name of that computer:
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