[Pdns-users] CNAME answer problem?

[bert hubert]

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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