Round robin on CNAME

Nate Campi nate at campin.net
Sun Mar 31 08:09:27 UTC 2002


On Sat, Mar 30, 2002 at 09:27:32PM -0500, William Stacey wrote:
> Here is how people like Yahoo and MS do it:
> www.yahoo.com.          1511    IN      CNAME   www.yahoo.akadns.net.
> www.yahoo.akadns.net.   287     IN      A       64.58.76.178
> www.yahoo.akadns.net.   287     IN      A       64.58.76.223
> www.yahoo.akadns.net.   287     IN      A       64.58.76.222

www.lycos.com is done this way, too. The reason for the CNAME is to get
a DNS service (from Akamai in this case) that gives out different
addresses depending on:

- where the querier is asking from (get a "closer" web cluster)
- the condition of the different web clusters that serve the site
- the condition of the network between the querier and the different
  clusters that serve the site
- whether or not a test object is live on each of the clusters that
  serve the site
- probably more that I can't think of at midnight

This has no relation to "multiple CNAME" entries, but what Akamai calls
"DNS Geo Load Balancing", if I remember the term correctly.

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. We'll see if they listen. If you're going to do it, you may
as well do it right.
-- 
Nate

Linux is like an indian's tent: 
No gates, no windows, and apache inside. 



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