|
TCPIP
Problem Solving 
1. Click Start |
Run then type winipcfg /all in Windows 9x,
or ipconfig /all at a Windows NT/2000/XP
command prompt to display your
TCP/IP configuration. Check to make
sure your IP address,
subnet mask and default gateway are correct.
Additionally, if your network uses WINS
or DNS, check to see that
those server addresses are correct.
If your configuration is incorrect, you
can modify it in Network properties.
2. Next, use Ping to test
IP connectivity:
Ping the loopback address of the host
having a problem. This will verify
that TCP/IP is installed and configured
properly on the computer.
ping 127.0.0.1 or ping loopback
Ping the IP address of the local
computer. This will verify that it was
added to the network correctly.
ping IP_address_of _local_computer
Ping the IP address of the default
gateway (router). This will verify the
router is working and you can communicate
with a host on the local network.
ping IP_address_of _default_gateway
Ping the IP address of remote host.
This will verify you can communicate
through the router..
ping IP_address_of _remote_host
3. If any of these Ping tests fail,
| check
: |
Is the TCP/IP protocol
installed on the computer? Check the
TCP/IP configuration. Is it correct? Does your network
use static IP addresses or dynamically assigned addresses (DHCP)?
|
Is your network
card listed correctly in Network properties?
Do you have the latest driver for your network card? |
If the first
2 Ping tests pass, but the third test fails, you may have
an
infrastructure problem. An infrastructure problem could
involve
cabling and/or the hub or switch your computer is attached to.
Also, the router may be down or not configured properly. |
If the first
3 Ping tests pass, but not the fourth, then you most likely
have a router configuration problem. Try to ping several
known good remote hosts. If they all don't respond, look
to the router for the problem.
|
Address
and Name Resolution
If you are able to
Ping a host using the Host's IP address, but cannot Ping
the host using it's name, then you have a Name Resolution Problem.
ping 191.107.32.18 - works
ping server1 - doesn't work
Host names are resolved to IP address depending on what type
of application
interface is used. There are 2 types, TCP/IP sockets names
and NetBIOS names.
Sockets applications include Ping, FTP, Telnet, WWW. NetBIOS
applications
would be net use, net view, and connecting to resources through
Network Neighborhood.
The following table shows how these names are resolved to IP address:
| Sockets
Names |
NetBIOS
Names |
| local
hostname |
local
hostname |
| then
HOSTS file |
netbios
cache first |
| then
DNS |
then
WINS |
| then
netbios cache |
then
Broadcast |
| then
WINS |
then
LMHOSTS file |
| then
Broadcast |
then
HOSTS file |
| and
finally LMHOSTS file |
and
finally DNS |
In order to use WINS and/or DNS, there must be a WINS and/or DNS
server
on your network, and your TCP/IP properties must be configured with
these
server's IP addresses.
In order to use a HOSTS or LMHOSTS file, these files must be created
and added to the computer.
NetBIOS Problem Solving
1. When
troubleshooting name resolution issues, it is important to narrow
down
whether the application is resolving a
NetBIOS name or a sockets name.
2. Once this is decided, you can look at the table
above to see what your
computer is configured for as far as name
resolution. Do you have a
WINS server added to your TCP/IP configuration,
or a DNS server?
If not, do you have a LMHOSTS or HOSTS
file.
3. If you do have the proper name resolution resource,
but are still unable to
resolve names to IP address, then look
to that resource as the fault point.
- Verify the IP addresses of the WINS and/or
DNS servers.
- Open the HOSTS and/or LMHOSTS files to
see if the device you are
trying to resolve is added.
- Ping the DNS or WINS server to make sure
it is actually there.
- Finally, if you have the proper resource
configured, it is on the network
(for example a DNS server),
but you still cannot resolve names, then it's
possible the resource (DNS
server) is not configured properly.
Utilities
to Troubleshoot Connectivity Problems
There are several Windows utilities
you can employ to help resolve network
connectivity problems. The following table lists some (but
not all) of these
utilities:
| Utility |
Description |
Example |
| ping |
tcp/ip utility
to verify a host exits. |
ping 162.56.62.47
ping myserver1 |
| tracert |
utility to
trace the route of a packet from
router to router until it reaches it's destination. |
tracert
162.56.62.47
tracert myserver1 |
| arp |
view and modify
arp table entries on a local
computer. shows ip addresses to MAC addresses. |
arp -a
arp -g
shows the arp cache
|
| nbtstat |
view and modify
the NetBIOS name cache.
can be used to get the MAC address of any
Windows computer. |
nbtstat
-c
shows the NetBIOS cache
including IP addresses
nbtstat -a <name>
<name> is a computer name
shows NetBIOS cache of <name> and that computer's MAC
address |
| netstat |
displays current
TCP/IP connections. can be
used to see if an intruder is connected to your PC
through a TCP or UDP port. |
netstat
-a
shows all TCP/IP connections
netstat -r
shows all TCP/IP connections plus the local routing table |
| ipconfig |
shows TCP/IP
configuration on a Windows NT
computer. |
ipconfig
shows partial IP configuration info
ipconfig /all
shows all IP configuration info |
| winipcfg |
shows TCP/IP
configuration on a Windows 9x
computer. |
winipcfg
shows partial IP configuration info
winipcfg /all
shows all IP configuration info |
The above utilities are run in a DOS
window or at a command prompt.
winipcfg can also be run from Start
| Run.
To see more information about each utility, type the utility name
plus /?.
example: netstat /? or arp /? (notice the space)
For more information about TCP/IP and NetBIOS issues check the Windows
Resource Kits, or you can search the Microsoft Knowledgebase:
http://support.microsoft.com/default.aspx?pr=kbinfo&
|
