topic Re: Issues with DNS resolution in Operating System - HP-UX

Issues with DNS resolution

Mogamat Kahaar — Fri, 11 Jan 2002 06:49:45 GMT

I have two "nameserver" entries in my /etc/resolv.conf file on my HPUX 11.00 server. When a host entry is not found in the first entry the resolver does not seem to query the second "nameserver" in the list (who does happen to have the requested host's IP details). I therefore get a "No address information available" message on the command line (when using nslookup).

Any ideas?

Thanks

Mo

Re: Issues with DNS resolution

Ravi_8 — Fri, 11 Jan 2002 07:17:21 GMT

Hi,
The domain name of both the DNS servers should be the same. other wise /etc/resolv.conf should look like

domain_name1
ip of the first DNS server
domain_name2
ip of the second DNS server

Re: Issues with DNS resolution

Stefan Schulz — Fri, 11 Jan 2002 07:17:47 GMT

Hi,

you have to check your /etc/nsswitch.conf for the hosts entry. If you have more than on dns servers configured, you also need to make sure that the second dns server is used.

Set NOTFOUND=continue. My hosts entry in the /etc/nsswitch.conf looks like:

hosts: files[NOTFOUND=continue UNAVAIL=continue] dns [NOTFOUND=continue UNAVAIL=continue T
RYAGAIN=continue] dns

which works fine with 2 dns servers configured.

Hope this helps

Regards Stefan

Re: Issues with DNS resolution

Mogamat Kahaar — Fri, 11 Jan 2002 07:38:09 GMT

Both nameserver entries have the same domain extension.

Also, my nsswitch.conf does have the entries as mentioned in the above response (Stephan's response).

I can also enter nslookup (without any host name) and then manually change to the secondary DNS server using the "server x.y.z.a" command and then enter the required node name. This returns the correct result.

Could it perhaps be that I require an OS patch?

Re: Issues with DNS resolution

Ravi_8 — Fri, 11 Jan 2002 07:54:58 GMT

Hi again

SAM-->Network communication-->DNS(Bind)-->DNS Resolver-->Action--> Specify the name servers in Querry order you like.

Re: Issues with DNS resolution

Stefan Schulz — Fri, 11 Jan 2002 08:21:52 GMT

Hmm if everything looks right but still isn't working, it might be a typo or a format problem in your configfiles.

I would first rename the resolv.conf and recreate it using SAM. This will make sure that the new created file has the correct format.

If this doesn't work do the same with the nsswitch.conf.

If it's still not working, feel froo to post those files here.

Hope this helps

Regards Stefan

Re: Issues with DNS resolution

Mogamat Kahaar — Fri, 11 Jan 2002 09:49:43 GMT

Attached is a winzip file containing my nsswitch.conf and resolv.conf

I have tried Stefan's suggestion of recreating the files via SAM and this did also not work.

Thanks

Mo

Re: Issues with DNS resolution

Eugen Cocalea — Fri, 11 Jan 2002 09:57:51 GMT

Hi,

What happens if you change the hosts line in your nsswitch.conf from

dns [blabla] files

to

files [blabla] dns

?

E.

Re: Issues with DNS resolution

Steven Gillard_2 — Fri, 11 Jan 2002 10:01:44 GMT

The problem is, if the first nameserver answers the query at all that is the answer that will be returned. The resolver will only fall back to the second nameserver in resolv.conf if the first query times out. So even if it responds with 'host not found' that is still a response and as such that is the answer returned. Unfortunately the NOTFOUND=continue configuration in nsswitch.conf has no control over this, it just specifies that the next policy should be tried which in your case is the hosts file.

The only solution to this problem is to fix the configuration of the name servers so that they are both able to resolve all names. If both servers are looking after the same zones why would you want to have different names in each?

Regards,
Steve

Re: Issues with DNS resolution

Mogamat Kahaar — Fri, 11 Jan 2002 10:07:16 GMT

Hi Steven,

Thanks for all the input.

Regards

Mo