Selective forwarding from an internal only name server

Barry Margolin barmar at
Thu Aug 18 01:07:48 UTC 2016

In article <mailman.301.1471466524.15653.bind-users at>,
 "Darcy Kevin (FCA)" <kevin.darcy at> wrote:

> Barry,
> 	Cloudflare has been doing this for a while, so that their customers won't be 
> "limited by the DNS specifications (RFCs)" <rolls eyes>. Having done that, 
> they were compelled to offer another service -- so-called "CNAME flattening" 
> -- to fix the brokenness that's caused by their base offering.
> See 
> C-compliant-support-for-CNAME-at-the-root
> I think Akamai also offers something similar.

But these don't work by sending an actual CNAME record. The server that 
implements flattening looks ip the IP of the target, and returns it as 
an A record for the domain.

That's why Cloudflare's method is "RFC-compliant", but what MS is doing 
with is not.

> 									- Kevin
> -----Original Message-----
> From: bind-users [mailto:bind-users-bounces at] On Behalf Of Barry 
> Margolin
> Sent: Wednesday, August 17, 2016 4:34 PM
> To: comp-protocols-dns-bind at
> Subject: Re: Selective forwarding from an internal only name server
> In article <mailman.299.1471461214.15653.bind-users at>,
>  "Darcy Kevin (FCA)" <kevin.darcy at> wrote:
> > Well, is a CNAME to, so you 
> > might need to make arrangements for that to be resolvable as well.
> That doesn't seem valid to begin with. The .COM zone has delegation NS 
> records for Having a CNAME record for the same name is wrong.
> --
> Barry Margolin
> Arlington, MA
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Barry Margolin
Arlington, MA

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