[Pdns-users] Empty CNAME will result "server can't find: NXDOMAIN"

Thomas Faddegon thomas at wapnet.nl
Sun May 6 20:48:44 UTC 2012


Tnx peter for your feedback. I'll try to find out what pipebackend is and
if I implement a workaround or not.

Regards,
Thomas
Op 6 mei 2012 10:26 schreef "Peter van Dijk" <peter.van.dijk at netherlabs.nl>
het volgende:

> Hello Thomas,
>
> On May 6, 2012, at 10:21 , Thomas Faddegon wrote:
>
> > Google and amazon use CNAME's instead of A to point to their webservers.
> Some example:
> http://blog.cloudflare.com/zone-apex-naked-domain-root-domain-cname-supp#!/
>
> amazon.com and www.amazon.com actually point to A records. Google.com
> points to A records that just serve redirs to www.google.com.
>
> What cloudflare is doing is either broken (if they really do put CNAMEs on
> apexes) or a hack where they do the A lookup (which breaks geo-based load
> balancing).
>
> > Amazon and Google have the right to modify the IP of their CNAME so if
> you use an A record to make http://example.com working and their modify
> the IP then http://example.com isn't working anymore.
>
> Yes, this is true.
>
> > I'll get more and more requests from customers that asked me to create
> an "apex cname" for there domains. Apex CNAME's in combination with
> Microsoft DNS works correctly (even the RFC isn't support this officially).
> Apex CNAME's in PowerDNS also works but the MX are broken after the change.
>
> Broken MX is just the first thing you noticed. Putting CNAMEs on an apex
> breaks many things in unpredictable ways. We very strongly recommend
> against it.
>
> > Is there any other way with PowerDNS to workaround this?
>
> You could do a pipebackend that does a fresh lookup of your CNAME target
> and returns the IPs. As noted above, this can break geo-based load
> balancing.
>
> Kind regards,
> --
> Peter van Dijk
> Netherlabs Computer Consulting BV - http://www.netherlabs.nl/
>
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