Host = domain

[Mark Andrews]

> On Wed, Jul 19, 2006 at 06:56:36PM +0200, Okka Dns wrote:
> > 
> > Works for me.
> > Using bind 9.2.3 
> ...
> > > www	A	@ 
> ...
> 
> 
> I was going to cite where in the ARM this wasn't possible, but ... I
> just grepped through the ARM and "@" is a completely undocumented
> feature.  ;-)  Which nevertheless everyone knows and uses.

	That's because it is documented in RFC 1034 / RFC 1035.

	The ARM documents the *extensions* to the master file format.
 
> Cricket Liu's "DNS and BIND" doesn't have "@" in the index!  But it's in
> Chapter 4, p. 68 of the Fifth Edition [you have gotten your 5e, right?
> ;-)].  Here it says that the domain name [the left-hand side] may be
> specified as "@" if it's the same as the origin.  It says NOTHING about
> it being usable as the right-hand side; but even if we for the moment
> accept the possibility of it being in the RHS, that would mean that the
> above says:
> 
> www	A	domain.tld
> 
> which is still illegal, as the domain is not the IP address.
> 
> Besides, any resource records for "www" do NOT affect the resource
> records for the domain itself!  The above does not do what the original
> poster wanted.
> 
> Several people have already commented that:
> 
> @	A	ip.ad.dr.ess
> 
> will work, and so it will.  But the original poster was ALSO correct
> that the following should work:
> 
> {empty space}	A	ip.ad.dr.ess
> 
> ... but ONLY when this follows something else whose LHS is the origin
> domain!  In other words, THIS will work:
> 
> $TTL	24h
> 
> @	SOA	...
> 
> 	NS	...
> 	NS	...
> 
> 	A	ip.ad.dr.ess
> 
> www	A	ip.ad.dr.ess
> 
> but the following will only generate TWO identical "A" records for
> "www":
> 
> $TTL	24h
> 
> @	SOA	...
> 
> 	NS	...
> 	NS	...
> 
> www	A	ip.ad.dr.ess
> 
> 	A	ip.ad.dr.ess
> 
> and the following generates an extra, incorrect A record for "foo":
> 
> $TTL	24h
> 
> @	SOA	...
> 
> 	NS	...
> 	NS	...
> 
> www	A	ip.ad.dr.ess
> foo	A	other.ip.addr.ess
> 
> 	A	ip.ad.dr.ess
> 
> -- 
> Joe Yao
> -----------------------------------------------------------------------
>    This message is not an official statement of OSIS Center policies.
> 
> 
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org