CNAMES across zones

[josephc at etards.net]

OK, I have somehow managed to start a holy war between sysadmins here
regarding CNAMES across zones. 

On the oneside you have people that believe that is a terrible thing to
do,
and others that see nothing wrong with it.

For example: (assuming this is fubars zone file)

www.fubar.net.		IN	CNAME	www.fubar.com.

The best example would be if a company had fubar.com, fubar.net, and
fubar.org as well as 100 other domains that they all wanted to point to
the
same host.

While 'a' records pointint to x.x.x.x would work, should that IP ever
change, or if it changes often, it would be a pain to update every zone
with the new IP. But if say fubar.com was the only domain that pointed www
to the IP via an 'a' record, then all the other domains could CNAME www  
to
www.fubar.com. There would be no CNAME's pointing to other CNAME's.

The only consequence I can see is a higher load on the DNS server. Are
there any other known porblems with this setup?

thanks

-joe