NS records and serial numbers

[Barry Margolin]

In article <bn14p9$6r0$1 at sf1.isc.org>,  <rmang at lexiconn.com> wrote:
>Our setup is 3 primaries, which we maintain via perl scripts. We 
>have chosen not to setup slave nameservers. That is why I am 
>asking what the implications are if the NS records are not identical / 
>missing one nameserver, or if the serial numbers are different, 
>etc...

The only thing the serial number is used for is a slave determining whether
it needs to perform a zone transfer.  If you have no slave servers, serial
numbers are irrelevant.

The implications of different NS records is that you may not get as good
redundancy as you would have otherwise.  The NS records that a particular
server gives out will be cached, and until their TTL expires that caching
server will only query those nameservers for the zone.  If all of those
nameservers die, the other nameservers that aren't in the NS records will
not be used until the TTL runs out and the caching server fetches the
delegation records from the parent zone's servers.

-- 
Barry Margolin, barry.margolin at level3.com
Level(3), Woburn, MA
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