topic Re: DNS Question in Operating System - HP-UX

DNS Question

ROSS HANSON — Mon, 09 Dec 2002 17:57:11 GMT

Can you have two primary DNS servers instead of a primary and
a secondary??

Thank You

Re: DNS Question

Kellogg Unix Team — Mon, 09 Dec 2002 18:06:58 GMT

Technically, yes. But that would imply that you now need to keep them in sync. Any change in one's data need to be reflected in other's. Of course, I am assuming that you are talking about the same zone. If you set the other one as secondary, the zone data are transferred.

Are you thinking of setting up split-DNS?
:-)

...Manjeet

Re: DNS Question

Byron Myers — Mon, 09 Dec 2002 18:11:57 GMT

Yes, The this is the design of the Internet. But as stated earlier, this is best suited for differing zones. Otherwise, you will have to manage synchronizing the two servers.

Re: DNS Question

ROSS HANSON — Mon, 09 Dec 2002 18:44:03 GMT

These are not differing zones,
if I get your meaning. These both will have the same information on them. But if one
goes down you can automatically
switch to the other

Re: DNS Question

Kellogg Unix Team — Mon, 09 Dec 2002 18:54:03 GMT

OK, I got it. This is one of the ways to provide redundancy. In client's /etc/resolv.conf (and equivalent PC file), you can enter IP addresses of both servers. In case one goes down, you will be served by second server, albit with a little delay.

...Manjeet

Re: DNS Question

John Bolene — Mon, 09 Dec 2002 19:55:21 GMT

syncronizing the servers is very easy, just set one up as secondary to the primary and have it pull its data from the primary

with lines such as

secondary mydomain.com server.ip.from.here dirs-to-copy

I have 2 root servers for my small internal domain which also forward internet lookups outside.

Setting up your resolv.conf with the primary then the secondary is easy. There is a delay in 10.20 if the primary cannot be found, but this is configurable in 11.

Re: DNS Question

Christopher Caldwell — Mon, 09 Dec 2002 20:42:18 GMT

From the client's perspective, there is little difference between primary and secondary servers. All authoritative name servers appear in the SOA record - you don't say one is primary and one is secondary.

From the server standpoint, secondaries "pull" zones from primaries - or in more modern versions of bind, primaries can push zones to secondaries.

It's certainly possible to configure all primaries (no secondaries) by hand building the zones on all of the relevent servers. You'll then have to devise a mechansim to keep the zones sychronized (in the case of the primary/secondary, synchronization is handled for you).

Re: DNS Question

ROSS HANSON — Mon, 09 Dec 2002 21:01:49 GMT

Ok I admit I am slow!
How do you get the primary to
"push" to the secondary??

Re: DNS Question

U.SivaKumar_2 — Tue, 10 Dec 2002 05:34:49 GMT

Hi,

yes , you can have two primary DNS servers with same data.

COnfigure DNS in two servers manually putting every entry for the same zone.

register these servers as DNS servers for your domain in the Internet.

This would work for static DNS environments ( No changes in DNS records ) .

But in Large (changing) DNS environments if you add a new record to one of the DNS server then you will have to add the same to the second server also manually.

regards,
U.SivaKumar

Re: DNS Question

Steven E. Protter — Tue, 10 Dec 2002 16:07:04 GMT

You can use cron to synch them up. It means using NFS or CIFS or rcp or scp, to copy files from one server to the other.

cron can then stop/start the deamon on the target server.

I use this methodology on a NSP web hosting setup I run personally on Linux.

For real realiability though, I should have the second DNS server at a different physical location.

Steve