Round robin on CNAME

[Barry Margolin]

In article <a87l4h$bp7 at pub3.rc.vix.com>, Nate Campi  <nate at campin.net> wrote:
>
>On Sun, Mar 31, 2002 at 11:09:33AM -0500, William Stacey wrote:
>> > The experts on this list undoubtedly noticed that Akamai uses a CNAME
>> > instead of simply delegating the domain name. I'm supposed to talk to
>> > the Akamai PD people this week to explain how delegation is more
>> > efficient.
>> 
>> Could you expand on that here too that we may also benefit?
>
>It's a small difference, but we're dealing with really busy domain names
>here, and small differences matter. When a CNAME is encountered, the
>query has to be rewritten with the new name. This costs in computing
>resources, adding latency. Following NS records without rewriting the
>query would be better.

I don't think it makes much difference.  Whichever type of record is used
will be cached, and then your server will go directly to the Akamai
nameserver.

The CNAME technique simplifies adding new names pointing to the same Akamai
webserver.  The customer adds a CNAME record to his DNS (pointing to the
same <something>.akadns.net name), Akamai adds the name to the virtual host
configuration of the webserver, and nothing needs to be done on the Akamai
nameserver.  NS delegation would require a third step of adding the
subdomain to the Akamai nameservers, and every additional step means one
more thing that can go wrong (remember the KISS principle).

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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