Beyond DNS...

Thu Jun 4 21:51:16 UTC 1998

> Err, they do. Here's how to set it up:  These balance the load, and if one
> machine is down, any browser which handles multiple A records properly will
> still fail over to the other machine.
> 
> 
> www             IN      CNAME   www1.av8.com.
>                 IN      CNAME   www2.av8.com.
> 
> www1            IN      A       198.3.136.144
>                 IN      A       208.156.100.250
> www2            IN      A       208.156.100.250
>                 IN      A       198.3.136.144

This also assigns more than one CNAME to the www label, which is a bad
idea.  You can force BIND (8.x) to allow it via "multiple-cnames yes",
but you'll probably get behavior you don't want since nameservers on
the net will cache just one of the CNAMEs (this isn't a problem in the
example above, but most people don't use the same set of addresses for
www1, www2, and so on).  The BIND configuration file guide says:

----------------------------------------------------------------------
multiple-cnames:
If yes, then multiple CNAME resource records will be allowed for a domain
name. The default is no. Allowing multiple CNAME records is against
standards and is not recommended. Multiple CNAME support is available
because previous versions of BIND allowed multiple CNAME records, and these
records have been used for load balancing by a number of sites.
----------------------------------------------------------------------

Just use multiple A records.

-- 
John Caruso, Director, System/Network Administration
CNET: The Computer Network          Email: caruso at cnet.com
150 Chestnut Street                 Phone: 415.395.7805 x1310
San Francisco, CA  94111            Fax:   415.623.2458