the secondary DNS option

[Nilzelio Monteiro]

Hi, I have a little problem. I have a HP-UX 10.20 with three DNS resolvers configured. But it is sending the DNS query just to the first one. Why? Any help is welcome.

Thanx

[A. Clay Stephenson]

Hi,

I would first check the format of /etc/resolv.conf.

e.g.
domain mycompany.com
nameserver 10.1.1.11
nameserver 10.1.1.21

If that is ok then I would use nslookup to make certain that both name servers are responding. It usually takes quite a few seconds for the resolver to give up on an entry and move on to the next.

Regards, Clay

[Kamlesh Shete]

Hi,

Basically whichever server is fast enough to handle the request services the call.

Are all your dns servers functioning? Primary, secondary etc.

You can force your client to use one particular server by
setting the YPBIND_OPTIONS field to -ypset and setting the YPSET_ADDR field to the ip address of the server.
This change is in the /etc/rc.config.d/namesvrs file

- KS

[Kamlesh Shete]

Hi,

The earlier posting was for selecting a particular NIS server not DNS. Sorry for the confusion. Clays answer fits well

- KS

[Patrick Wallek]

The nameserver entries in the resolv.conf file control the order in which the servers will be queried if one of them is not available.

Take an example:

nameserver machinea
nameserver machineb
nameserver machinec

In this case if you submit a DNS query it will first try to go to machinea. If DNS on machinea is not available, the query times out, and moves on to machineb, if machineb is available it will attempt to locate the target of the query. If the target of the query is not in DNS, then the query will fail, it will NOT move on to machinec.

nslookup will start with the first machine in the list, if the query times out, it will go to the second, and then the 3rd (there is a max of 3 entries for nameserver). It will NOT load balance queries across the 3 entries, nor will it move to another machine if the DNS entry it is looking for is not available on the first machine.

Check the man page for resolv.conf for more information.

[John Bolene]

What happens on my setup is that almost all requests go to the first name in the list, but a few do get to the other servers.
I can tell this by turning on the debug option on the second and third servers and observe how often they get hit.
The first server is always available unless it is being patched and has been available for 617 days now.