Resolving name server host problems

Use this procedure to resolve host name server problems.

If you cannot get a host name resolved:

Verify that the named daemon is active by issuing the following command:
```
lssrc -s named
```
Verify that the address of the target host exists and is correct in the name server database.
Send a SIGINT signal to the named daemon to dump the database and cache to the file /var/tmp/named_dump.db. Verify that the address you are trying to resolve is there and is correct.
Add or correct name-to-address resolution information in the named hosts data file for the controller name server of the domain. Then issue the following SRC command to reread the data files:
```
refresh -s named
```
Verify that the name resolution requests are being processed.
To do this, enter the named daemon from the command line and specify a debugging level. Valid debug levels are 1 through 9. The higher the level, the more information the debug mechanism logs.
```
startsrc -s named -a "-d DebugLevel"
```
Check for configuration problems in the named data files.
For more information, see Name server resolution - BIND version 9.4. In addition, see the "DOMAIN Data File Format,", "DOMAIN Reverse Data File Format," "DOMAIN Cache File Format," and the "DOMAIN Local Data File Format" in the Files Reference.
Note: A common error is the incorrect use of the . (period) and the @ (at sign) in the DOMAIN data files.

If external users cannot reach your domains, make sure that all your non-master name servers (worker, hint) have equal time-to-live (TTL) information in the DOMAIN data files.

If external resolvers query your servers constantly, make sure your servers are distributing DOMAIN data files with reasonable TTL values. If the TTL is zero or another small value, the data you transfer times out very quickly. Set the minimum value in your start of authority (SOA) records to a week or more to solve this problem.