> Lots of systems get really upset if you try to assign multiple
hostnames
> to
> the same tcpip stack. 

That's what CNAME records in the DNS are for. 

I create a DNS forward and reverse for each interface (canonical
name-interface, eg foo-eth0, foo-hsi0, etc.). The "hostname" that I
configure as /etc/hostname is a CNAME pointing to the appropriate
interface, which makes it nicely portable. Most of the complaining about
multiple entries pointing to an address is caused by the forward entry
not matching the reverse entry. CNAMEs force another DNS recursion to
get the info of the actual interface, which has forward and reverse
matching, and everyone's happy. If it's mail, you need MX and SPF
records as well. 

If I want a pointer to a host from the same zone or another zone, I can
use a CNAME to the FQDN of the interface I want to use. 

It's a little more work, but it's really flexible, and helps a lot when
you start doing VIPA and other tricks. 

Example: Linux guest vm1foo01.guest.com has two interfaces, one external
Ethernet, one internal hipersocket. In my guest.com DNS zone I have:

vm1foo01-eth0           IN      A       123.45.67.89
vm1foo01-hsi0           IN      A       10.11.12.13
vm1foo01                        IN      CNAME   vm1foo01-eth0

In the reverse zone files, we create: 

123.45.67.zone:
89                              IN      PTR     vm1foo01-eth0.guest.com.

10.11.12.zone: 
13                              IN      PTR     vm1foo01-his0.guest.com.

Users in guest.com refer to vmfoo01, and they get the vm1foo01-eth0
address.  Any host that actually checks forward and reverse matches has
to follow the CNAME pointer to the canonical entry, and those entries
always match correctly. 

Another host might create a DNS entry for vm1foo01, but want to refer to
the hipersocket interface only. They create:

vm1foo01                        IN      CNAME vm1foo01-hsi0.guest.com

and any reference they make to vm1foo01 goes to the hipersocket
interface. 

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