Why two lookups for a CNAME?

[Phil Mayers]

On 22/10/15 16:30, Steve Arntzen wrote:

> As a test, I tried forwarding (and forward only) google.com to Google's
> public DNS server.  Although the packets did go directly to 8.8.8.8 as
> expected, my Bind server still (for safe verification) performed the
> second look up.  Note, the requesting client using dig, sends out one
> request and receives one reply.  The test was for "play.google.com".

"forward only" was going to be my suggestion but I guess it doesn't 
work. Likely it's just not implemented to avoid proliferation of code paths.

I wonder if the prefetch feature of recent versions of bind would help 
you; you'd still be doing the queries, but "in advance" of the cache 
entry expiring, so the client wouldn't see the slow, expired-cache case.