NS query returns NS records in random order

Kevin Darcy kcd at daimlerchrysler.com
Sat Jan 6 02:03:10 UTC 2001


BIND doesn't support strict ordering of NS'es because it does not
consider NS order significant. It is assumed (er, *required*!) that all
NS'es listed for a zone give the same answer content for a given query
in that zone, notwithstanding transitory zone-transfer propagation
delays. So why should the NS order matter? You'll get the same answer no
matter what.

Having said that, as a performance and reliability optimization, most
nameserver implementations -- notably BIND and I believe many others --
will keep track of how quickly other NS'es answer, and will prefer
faster NS'es over slower ones. So if you're wanting to impose a strict
ordering on NS'es for performance/capacity reasons, this should be
unnecessary. Load-balancing and failover between NS'es happens
automatically.

If you want to impose strict ordering for some *other* reason besides
performance/capacity, then you need to re-think whatever it is you're
trying to accomplish, because you're challenging one of the fundamental
assumptions of DNS. Perhaps it would help if you describe your ultimate
goal here. Maybe we can assist in finding a workable solution.


- Kevin

vranitzky at my-deja.com wrote:

> Hi!
>
> I have several domains on my BIND server, all with
> the same NS records;
> here's an example of one of the zone files on the
> master
> (dazio.dnsalias.net):
> -----
> eosconsulting.it.    1D    IN    SOA
> dazio.dnsalias.net.
> vran.primiero.com. (
>            2001010401
>            10800
>            3600
>            604800
>            86400 )
>
>        1D IN    NS    dazio.dnsalias.net.
>        1D IN    NS    someda.dnsalias.net.
> -----
> My problem is that when I do a
>
> nslookup -type=ns eosconsulting.it.
>
> I sometimes get first the primary, other times I
> get first the secondary.
> I absolutely need to get ALWAYS the primary
> (dazio.dnsalias.net) first!
>
> Is there a way to achieve this ??
>
> Thanks,
> Michael Scalet
> vran at mail.com
>
> Sent via Deja.com
> http://www.deja.com/






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