Choosing authoritative nameservers

[Elias]

Thanks for the reply sir! Just to share, I've finally figured out why my 
traces always seem to be hitting ens2.bursamalaysia.com no matter what I do. 
A packet dump actually shows requests being sent out to both 
ens1.bursamalaysia.com and ens2.bursamalaysia.com but somehow only 
ens2.bursamalaysia.com answers my queries (with a broken answer to boot!). 
I've tried changing my source IP and voila ens1.bursamalaysia.com suddenly 
starts answering again. They must really have some strange things going on 
their network. Their SOA does not list any valid contacts and their WHOIS 
contact isn't bothered to respond...just great...


----- Original Message ----- 
From: "Matus UHLAR - fantomas" <uhlar at fantomas.sk>
To: <bind-users at lists.isc.org>
Sent: Wednesday, June 02, 2010 8:39 PM
Subject: Re: Choosing authoritative nameservers


> On 02.06.10 16:20, Elias wrote:
>> Does anyone know how BIND chooses which authoritative server to refer to?
>> When a referal returns ns1.abc.com, ns2.abc.com and ns3.abc.com, will the
>> recursive server randomly send out a request to either ns1, ns2 or ns3 or
>> is there a selection algorithm?
>
> there's algorithm preferring the server with fastest responses but
> ocasionally tryiong other servers.
>
>> I've got a problem resolving www.klse.com.my and its probably caused by a
>> broken server along the path. But the problem is I keep hitting the same
>> server everytime no matter how many times I flush my caches.
>
> it's most probably not caused by server selection in BIND but in broken
> delegation.
>
> this is provided by com.my. sevrers:
>
>> klse.com.my.            86400   IN      NS      ens1.klse.com.my.
>> klse.com.my.            86400   IN      NS      ens2.klse.com.my.
>> ;; Received 103 bytes from 61.6.38.139#53(ns5.jaring.my) in 6 ms
>
> ens1.klse.com.my.       86400   IN      A       211.25.178.3
> ens2.klse.com.my.       86400   IN      A       121.123.146.80
>
> This is provided by delegated servers:
>
> ;; ANSWER SECTION:
> klse.com.my.            28800   IN      NS      ens1.bursamalaysia.com.
> klse.com.my.            28800   IN      NS      ens2.bursamalaysia.com.
>
> ;; SERVER: 211.25.178.3#53(211.25.178.3)
>
> klse.com.my.            28800   IN      NS      ens1.bursamalaysia.com.
> klse.com.my.            28800   IN      NS      ens2.bursamalaysia.com.
>
> ;; SERVER: 121.123.146.80#53(121.123.146.80)
>
>
> - we can safely say STOP here, the delegation is broken, fix it.
>
>
> However, looking at bursamalaysia.com domain... Delegation:
>
> ;; AUTHORITY SECTION:
> bursamalaysia.com.      172800  IN      NS      ens1.bursamalaysia.com.
> bursamalaysia.com.      172800  IN      NS      ens2.bursamalaysia.com.
>
> ;; ADDITIONAL SECTION:
> ens1.bursamalaysia.com. 172800  IN      A       211.25.178.3
> ens2.bursamalaysia.com. 172800  IN      A       121.123.146.80
>
>
> while ens1.bursamalaysia.com. returns same list of namservers, but does 
> not
> return glue records for them, the ens2.bursamalaysia.com. returns SERVFAIL
> for bursamalaysia.com.
>
> It's even more broken.
>
>
> -- 
> Matus UHLAR - fantomas, uhlar at fantomas.sk ; http://www.fantomas.sk/
> Warning: I wish NOT to receive e-mail advertising to this address.
> Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
> Fighting for peace is like fucking for virginity...
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