Point domain name of my zone to name in somebody else's zone?

Barry Margolin barmar at alum.mit.edu
Fri May 9 00:36:20 UTC 2014

In article <mailman.189.1399586996.26362.bind-users at lists.isc.org>,
 Mark Andrews <marka at isc.org> wrote:

> > Arguably adjusting CNAME to allow it to coexist with other record types 
> > might be a better long-term solution, perhaps allowing CNAME to coexist 
> > with SOA, NS and DNAME records?
> But that does not help when you want a MX record at the apex or
> some other record at the apex.
> CNAME is not and never has been the correct solution for this.  The
> problem is that CNAME "works" for www.example.net because only
> address records are put at www.example.net.  This covered 99.9% of
> use initially.

What people probably expect is for CNAME to be used as a default for any 
record types that aren't explicitly listed in the zone.

The problem with this is that it doesn't coexist with caching. 
Authoritative servers know which record types are in the zone, but 
caching servers only know the subset that they've recently looked up.

As you say, SRV was created to fill this gap in the DNS design. But it's 
never gotten traction because DNS administrators have always come up 
with ways to fake things out on the servers, so browser vendors have not 
had much incentive to implement the client side.

Barry Margolin
Arlington, MA

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