DNAME usage?
Chris Buxton
clists at buxtonfamily.us
Fri Nov 17 18:30:07 UTC 2017
A DNAME is a CNAME generator for subdomains of the DNAME record itself. That is:
example.com <http://example.com/>. DNAME example.net <http://example.net/>.
will result in any query for "foo.example.com <http://foo.example.com/>" to be answered with a dynamically-generated CNAME record like this:
foo.example.com <http://foo.example.com/>. DNAME foo.example.net <http://foo.example.net/>.
It has no effect on the name of the DNAME record itself -- it is not a CNAME record for example.com <http://example.com/>, and doesn't do the same job. The use case you describe cannot be solved by RFC-compliant DNS -- the name of a zone cannot be an alias of some other name. Creating the parent zone and putting the CNAME in there will create more problems for you.
Regards,
Chris Buxton
> On Nov 17, 2017, at 9:19 AM, Jeff Sadowski <jeff.sadowski at gmail.com> wrote:
>
> I am a bit confused by DNAME's
> I had used them before but I may have used them wrong.
>
> On windows 2008r2 I have some zone's where I create a DNAME for the
> root and point it to an A record.
>
> IE:
>
> zone bla.bla
> SOA <standard SOA>
> NS <mydns>
> DNAME www.bla.com
>
> where www.bla.com is an A record.
>
> the reason I was doing this is because www.bla.com has a dhcp assigned address
>
> and I want bla.bla to always point to it.
> windows dns does not allow a cname at the root of a zone.
>
> as of 2012r2 with updates this no longer works.
>
> So I decided to see what bind would do with DNAME If I tried a similar
> experiment
> I have a db.self file I used when I want certain outside addresses to
> point back to my inside addresses.
>
> my db.self file looks like so
>
>
> $TTL 3D
> @ 1D IN SOA ns jeffsadowski.gmail.com. (
> 2017081201 ;
> 3H ;
> 15 ;
> 1w ;
> 3h ;
> )
> @ IN NS ns
> ns IN A 192.168.1.252
> @ IN A 192.168.1.252
>
> And I wand similar for my DNAME so I created db.dname that looks like so
>
> $TTL 3D
> @ 1D IN SOA ns jeffsadowski.gmail.com. (
> 2017081201 ;
> 3H ;
> 15 ;
> 1w ;
> 3h ;
> )
> @ IN NS ns
> ns IN A 192.168.1.252
> @ IN DNAME methanemaker.mooo.com
>
> then when I try and start bind I get error messages like so
>
> Nov 17 09:55:53 methanemaker bash[7049]: zone bla.bla/IN: NS
> 'ns.bla.bla' is below a DNAME 'bla.bla' (illegal)
> Nov 17 09:55:53 methanemaker bash[7049]: zone bla.bla/IN: not loaded
> due to errors.
>
> I tried without the NS likes and I get this message
>
> Nov 17 09:48:36 methanemaker bash[4872]: zone bla.bla/IN: has no NS records
> Nov 17 09:48:36 methanemaker bash[4872]: zone bla.bla/IN: not loaded
> due to errors.
>
> If anyone has a better idea how to map to a dhcp addressed machine
> from a zone I'd like to know?
>
> I don't want to recreate the entire superdomain for just one record
> that needs changed
> IE:
> the super domain is managed by an outside service. I don't want to
> keep a second copy inside that has a few with different records.
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