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A few notes on TCP/IP to help with your troubleshooting

Host Name Resolution

This is the process of resolving the destination host name to an IP address. The sources and the order they are searched are:

  1. Computer checks its own name
  2. Local HOSTS file
  3. DNS server(s) (if configured)
  4. Local NetBIOS name cache
  5. WINS server (if configured)
  6. B-node broadcasts
  7. Local LMHOSTS file

The above process ends as soon as a source resolves the destination host name.

NOTE: The first IP address found is used. If there are multiple entries in different locations all subsequent entries will be ignored.

If none of the sources contain the correct mapping for the destination host name, the following error message is generated: 

Bad IP address hostname

NetBIOS Name Resolution Order

  1. NetBIOS name cache
  2. WINS
  3. B-node broadcast
  4. LMHOSTS
  5. HOSTS
  6. DNS

Subnet Reference

Subnet Mask Binary Bits Subnets Class C Addresses Class B Addresses Class A Addresses
192
11000000
2/6
2
62

16,382

4,194,302
224
11100000
3/5
6
30

8,190

2,097,150
240
11110000
4/4
14
14

4,094

1,048,574
248
11111000
5/3
30
6

2,046

524,286
252
11111100
6/2
62
2

1,022

262,142
254
11111110
7/1
126
0

510

131,070
255
11111111
8/0
254
0

254

65,534

When to Use Each TCP/IP Utility

Use netstat when you want to examine protocol statistics and network connections from the time the computer was first booted.

Use nbtstat to view the NetBIOS name cache, local or remote, and to purge and reload names.

Use ping to verify connectivity between two TCP/IP machines, either local or remote, and to determine if TCP/IP has initialised correctly on the local machine.

Use the Performance Monitor when you need to continually monitor activity, monitor activity at certain intervals, log into a file, establish a performance benchmark and create reports based on performance. You can create alerts when certain thresholds are reached.

Use the Network Monitor to capture packets for troubleshooting, monitor network bandwidth, and create triggers (alerts) to have actions performed based on specific events. You can also create filters to limit the amount of information that is captured or displayed, as well as capture packet information at certain intervals.

Use Telnet to provide terminal emulation to another TCP/IP device running the Telnet server service.

Use rexec (remote execute) to run commands on a server that is running the REXEC service (daemon). rexec authenticates the user name before executing the command.

Use rsh (remote shell) to run commands on a remote server. rsh does not provide authentication.

Use rcp (remote copy) to copy files from the TCP/IP client to the server. The RSH service (daemon) must be running on the server.

Use lpr to print to a TCP/IP host running the Microsoft TCP/IP Printing Service (daemon).

Use lpq to check the queue of a TCP/IP printer.

Use route to display the route table, and to add, modify, and delete the route entries.

Use tracert to trace the path a packet makes across routers in order to determine how long the transmission takes, as well as determine the last router passed before failure.

Use ipconfig to display the current machine's TCP/IP settings, such as IP address, subnet mask, and default gateway. ipconfig can also renew and release IP address leases.

Use the ipconfig/all command to show more-detailed TCP/IP settings information, such as the DNS and WINS server addresses, and to determine if IP routing or the WINS proxy is enabled.

Use ARP to display the IP address to hardware (physical) address mappings for a machine. You can also add, modify, and delete mappings.