*BSD News Article 70950


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From: j@ida.interface-business.de (J Wunsch)
Newsgroups: comp.unix.bsd.bsdi.misc
Subject: Re: named help...
Date: 14 Jun 1996 08:54:33 GMT
Organization: interface business GmbH, Dresden
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Reply-To: joerg_wunsch@interface-business.de (Joerg Wunsch)
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cavenerl@nbnet.nb.ca (Lance Cavener) wrote:

>  Just wondering.. I set up my DNS daemon with all the aliases for my
> system, and I added the IP addresses for my secondary servers
> (config_dns) so everything should work.. Anyway, how do the secondary
> servers (and every other DNS server in this world) know that I created
> thoes aliases?

The secondaries pick it up based on the increasing serial number in
the SOA record.  (That's why you should not forget to bump it.)  They
regularly query the SOA of the primary, and pull the entire zone file
once it has been increased.

All other servers query back at the authoritative server (either
primary or secondaries) once the time to live has expired.  Thus, the
default TTL in the SOA (or the actual TTL in each record) determines
the average DNS propagation latency.  If you make it low, latency for
new changes will be short, but your authoritative servers get much
more DNS traffic since all the caching servers in the world are forced
to discard the entry quickly.

-- 
J"org Wunsch					       Unix support engineer
joerg_wunsch@interface-business.de       http://www.interface-business.de/~j