[Pdns-users] CNAME answer problem?

Joyce LAMBERT lambert.joyce at gmail.com
Fri Aug 10 11:16:50 UTC 2007


Thank you for this reply

Do you know in witch RFC we can find this 'Algorithm', it seem that the
cname reply with servfail is a problem for some web hosting and for DNSSTUFF

*Server failure! [took 171 ms]. Response: Server failure. There's a problem
with the DNS server for WWW.abcde.com.*



2007/8/10, bert hubert <bert.hubert at netherlabs.nl>:
>
> On Fri, Aug 10, 2007 at 07:34:51AM +0200, Hannes M. wrote:
> > i have some strange problem with CNAME records to an external domain.
> > For example:
>
> This is a commonly observed oddity of the domain name system.
>
> Indeed, powerdns returns a 'servfail' if you ask it for www3.example.com,
> but it turns out that resolving nameservers ('recursors') know about that.
>
> The reason powerdns needs to return servfail is because it cannot
> faithfully
> answer the question - it does not know about 'www.somewhere-else.com',
> that
> domain is 'out of its bailiwick' in DNS speak.
>
> However, recursors get the hint and continue resolving for
> 'www.somewhere-else.com'.
>
> So what you observe is the 'SERVFAIL', because you did not configure
> powerdns to resolve for you.
>
> If you'd include a line 'recursor=4.2.2.1' for example, you would get a
> complete answer, because in that case powerdns would offload the
> processing
> of www.somewhere-else.com to the configured recursor.
>
> For www.example.com this won't work as it is a fake domain, but you get
> the
> idea.
>
> > dig +norecurs www3.example.com delivers the CNAME as stored, but PDNS
> > does not resolve.
>
> Well, that is as it should be.
>
> Good luck!
>
> --
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> http://netherlabs.nl              Open and Closed source services
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