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HOW TO: Diagnose and Test TCP/IP or
NetBIOS Network Connections in Windows 2000
The
information in this article applies to:
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Microsoft Windows 2000 Server |
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Microsoft Windows 2000 Advanced Server |
SUMMARY
This article provides
information about how to diagnose and test Transmission Control
Protocol/Internet Protocol (TCP/IP) or NetBIOS network configurations. This
article also describes the use of the most common diagnostic tools along with
basic network analysis techniques.
Your Computer Configuration
When
you want to troubleshoot a TCP/IP networking problem, first check the TCP/IP
configuration of the computer that is experiencing the problem.
To View the TCP/IP Configuration by Using
the Ipconfig.exe Tool
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Click Start ,
click Run , type cmd , and then press ENTER.
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At the command prompt,
type ipconfig , and then press ENTER. This command displays your
computer's DNS suffix, IP address, subnet mask, and default gateway.
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If you need more
information and want to display a detailed configuration report, type
ipconfig /all at the command prompt, and then press ENTER.
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Confirm that your
computer has the appropriate settings for DNS and WINS servers, an available
IP address, the proper subnet mask, the proper default gateway, and the
correct host name.
To Display Connection Information by
Using the Nbtstat.exe Tool
NetBIOS over TCP/IP (NetBT) resolves NetBIOS names to IP addresses. TCP/IP
provides many options for NetBIOS name resolution, including local cache lookup,
WINS server query, broadcast, DNS server query, and LMHOSTS and HOSTS lookup.
Nbtstat.exe is a useful tool for troubleshooting NetBIOS name resolution
problems. You can use the nbtstat.exe command to remove or correct
preloaded entries. To use the nbtstat.exe command:
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To list the NetBIOS
table of the local computer, type nbtstat -n at the command prompt, and
then press ENTER. This command displays the names that were registered locally
on the computer by programs such as the server and redirector. |
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To list the contents of
the NetBIOS name cache, type nbtstat -c at the command prompt, and then
press ENTER. This command shows the NetBIOS name cache, which contains
name-to-address mappings for other computers. |
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To purge the name cache
and reload it from the LMHOSTS file, type nbtstat -r at the command
prompt, and then press ENTER. |
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To perform a NetBIOS
adapter status command against the computer that you specify by name, type
nbtstat -a NetBIOS computer name at the command prompt, and then
press ENTER. The adapter status command returns the local NetBIOS name table
for that computer and the MAC address of the network adapter. |
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To display a list of
client and server connections, type nbtstat -s at the command prompt,
and then press ENTER. This command lists the current NetBIOS sessions and
their status, including statistics, as shown in the following example:
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NetBIOS Connection Table
Local Name State In/Out Remote Host Input Output
------------------------------------------------------------------
DAVEMAC1 <00> Connected Out CNSSUP1<20> 6MB 5MB
DAVEMAC1 <00> Connected Out CNSPRINT<20> 108KB 116KB
DAVEMAC1 <00> Connected Out CNSSRC1<20> 299KB 19KB
DAVEMAC1 <00> Connected Out STH2NT<20> 324KB 19KB
DAVEMAC1 <03> Listening
Testing Connections to Remote Servers
If
you are unable to contact to a remote server, there are two common tools that
you can use. Use the ping command to verify that a host computer can
connect to the TCP/IP network and network resources. Use the tracert
command to examine the route taken to a destination.
To Test Connections by Using Ping.exe
You
can use the ping command as a troubleshooting tool to sequentially test
connectivity to various network resources. To ping a network host directly:
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Click Start ,
click Run , type cmd , and then press ENTER.
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Type ping IP
address of the remote network host (for example, ping 192.168.1.104)
or ping host name (for example, ping www.microsoft.com), and
then press ENTER.
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Check for a reply that may look like this:
Reply from 192.168.1.104:
bytes=32 time=40ms TTL=61
If this message displays,
the server is available on the network. If you are unable to contact the
resource, you can troubleshoot the connection by using the ping command
to test connectivity to various network resources:
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Ping the loopback
address (by using the ping 127.0.0.1 command) to verify that TCP/IP
is installed and working correctly on the local computer.
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Ping the IP address of
the local computer to verify that it was added to the network correctly.
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Ping the IP address of
the default gateway to verify that the gateway is functional and it is
possible to connect to a local host on the local network. You can obtain the
IP address of the local default gateway by using the ipconfig
command.
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Ping the IP address of
another remote host to verify that you can communicate through a router.
To Test Connections by Using Tracert.exe
Tracert.exe is a route-tracing utility that you can use to determine the network
path to a destination. To determine the path that a packet takes on the network
and where that path may be ending:
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Click Start ,
click Run , type cmd , and then press ENTER.
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At the command prompt,
type tracert IP address of the remote network host , and then
press ENTER.
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Examine the results to
determine the length of time that the packet took to reach each network
segment and the point at which the connection may stop working.
To Test Connections by Using the NET VIEW
Command
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Click Start ,
click Run , type cmd , and then press ENTER.
- At
the command prompt, type net view \\ computer name , and then
press ENTER. A list of the file and print shares of a computer that is running
Windows 2000 is generated by establishing a temporary NetBIOS connection. If
there are no file or print shares available on the specified computer, you
receive a "There are no entries in the list." message. If the command does not
work, type net view \\ IP address of the remote computer , and
then press ENTER. If the command works, but a net view attempt to the computer
name does not work, the computer name may be resolving to the wrong address.
If the command does not work and generates a "System error has occurred" error
message, verify that you typed the correct name of the remote computer, that
the computer is operational (and is running the File and Printer Sharing for
Microsoft Networks service), and that all of the gateways (routers) between
the local computer and the remote host are operational by using the ping
command.
BY: MRA - 06/2002
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