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Date: Wed, 29 Jan 1997 09:07:02 +1100 (EST)
From: "Daniel O'Callaghan" <danny@panda.hilink.com.au>
To: pumpkin@uk.pi.net
cc: FreeBSD ISP list <freebsd-isp@freebsd.org>
Subject: Re: Multiple IP addresse, hostnames on one machine
In-Reply-To: <Pine.BSI.3.95.970128105423.314C-100000@Zero-Cool.Hades.Org>
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On Tue, 28 Jan 1997 pumpkin@uk.pi.net wrote:

> On Tue, 28 Jan 1997, Daniel O'Callaghan wrote:
> 
> > [......]
> > Note that a CNAME record *must* point to an A record, not to another CNAME.
> >
> 	Why not?   It works for me:
> 
> 	(zone file)
> 	Zero-Cool	IN	A	10.10.10.1
> 	WWW		IN	CNAME	Zero-Cool
> 	test		IN	CNAME	www
> 
> 	(scot@Zero-Cool) ~ >nslookup test
> 	Server:  localhost.Hades.Org
> 	Address:  127.0.0.1
> 
> 	Name:    Zero-Cool.Hades.Org
> 	Address:  10.10.10.1
> 	Aliases:  test.Hades.Org, www.Hades.Org
> 
> 	It seems to resolve OK doesn't it?

With a double lookup.  What a waste of bandwidth.
Q whois test?
A test=WWW
Q whois WWW?
A WWW=Zero-Cool, IP=10.10.10.1

Another common misconfiguration is pointing an MX at a CNAME, e.g. 
hades.org. IN MX 10 test.hades.org.
(Generates error "hades.org has CNAME and other data").

> > 1.  The aliased address is part of the same subnet/network as the primary 
> >     address.
> > 
> > In this case, you need to specify a netmask of 0xffffffff (8 f's) and put 
> 
> 	I've heard of this before... but I can't find anyone who can tell
> me why the netmask has to be different.  Personally I don't specify
> a netmask for the aliases and it seems to work out OK.   Any offers?

What version of FreeBSD are you running?  In the later versions, the 
netmask 0xffffffff is required.  I think it might be to do with 
preventing broadcasts multiple times on each interface, but perhaps the 
person who made it like that can comment.

Danny