Information Technology Reference
In-Depth Information
-
On a UNIX platform, type
cat /etc/resolv.conf
at a command prompt.
2.
Verify that you can ping the name server using its IP address. If the ping fails, go to the section
“Narrowing Down the Problem Domain,” earlier in this chapter, to troubleshoot connectivity
between the client and the name server.
3.
Verify that you can resolve names within your domain. (For example, if your host is Host1.test.com,
you should be able to resolve the names of other hosts in the test.com domain, such as
host2.test.com.)
4.
Verify that you can resolve one or more domain names outside your domain.
If you cannot resolve names from all domains except that of the destination, there might be a problem
with the DNS for the destination host. Contact the administrator of the destination device.
If you cannot resolve names within your domain or a large number of external domains, contact your
DNS administrator because there may be a problem with the local DNS (or your host could be using the
wrong domain server).
Before Calling Cisco Systems' Technical Assistance Center
Before calling Cisco Systems's Technical Assistance Center (TAC), make sure that you have read
through this chapter and completed the actions suggested for your system's problem.
Additionally, do the following and document the results so that the Cisco TAC can better assist you:
•
Have a network diagram of your network or affected portion of your network ready. Make sure that
all IP addresses and their associated network masks or prefix lengths are listed.
•
Have any information that you gathered thus far while troubleshooting available for the TAC
engineer.
•
If the problem appears to be with only a few—fewer than four—routers, capture the output from
show tech
on these routers.
Dial-in or Telnet access also help considerably in effective problem resolution.
For More Information
For further information, including step-by-step configuration materials and full command examples for
most IP-related commands, you can consult the following topics and web pages:
•
The Technical Assistance Center (TAC) web site on Cisco Connection Online (CCO), at
www.cisco.com/tac
•
The Cisco IOS online documentation on CCO, at www.cisco.com
•
Stevens, W. Richard.
TCP/IP Illustrated, Volume 1
. Addison-Wesley.
•
Comer, Douglas E.
Internetworking with TCP/IP, Volume I.
Prentice Hall.