all machines all subdomains to one ip

[Jeff Lasman]

David D wrote:

> I m newbie.
> I ve read the linux dns howto.
> I find nothing to do something as simple as telling all machines of a domain
> are in the following ip.

How do you plan on getting multiple machines to answer on one IP#
without breaking your network?

More likely you'd have multiple services, each with their own subdomain
name, though you _could_ have multiple machines look like they're
answering the same IP# (though not actually doing it) on a NATted
network.

> Is it possible ?
> 
> Simple as :
> *.domain.com -> xxx.xxx.xxx.xxx

I've only got the 3rd Edition in my library, but I'd recommend you get
the 4th Edition of DNS and Bind, and look in the index for "wildcards".

There are a few reasons why you might want to do it, and some important
reasons why you wouldn't.

And there's one important "gotcha"... if any record in your zonefile
defines any subdomain resolution, then the wildcard won't work for that
subdomain.

For example, if you've got A records as follows

a.example.com.	1D	IN A	123.45.67.8
b.example.com.	1D	IN A	123.45.67.8

and a single wildcard mx record:

*.example.com.	1D	IN MX 10	example.com.

Then the MX record won't be returned for MX lookups for either
a.example.com or for b.example.com, but it would be returned for MX
lookups for example.com, and for www.example.com, which may or may not
be what you desire.

(Unless there are A, CNAME, NS or other records for example.com, for
www.example.com, in which case they won't be returned for them, either.)

(My reference is "DNS and Bind", 3rd edition".)

You'd be much better off with explicit records; that way you know what
you're getting.

Jeff
-- 
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