Host = domain
Mark Andrews
Mark_Andrews at isc.org
Wed Jul 19 22:42:22 UTC 2006
> 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
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