Re: domain name
On Sat, Sep 1, 2012 at 5:49 PM, Glenn English <ghe@slsware.com> wrote:
> On Sep 1, 2012, at 3:15 PM, John Hasler wrote:
>>
>> The kernel has no interest in domain names. It deals only in IP
>> numbers. Dealing with DNS is the job of a resolver running in user
>> space.
>
> Thanks. I didn't know that -- makes sense. But it raises a question in
> my mind: Who does, beside servers? Just 'hostname'?
>
> I think I came into the TCP/IP networking business a little late. Was
> there ever a time when there were no domains, just IPs? That could
> explain a lot to me about why the domain name is so hard to get to...
>
>> A machine can be in more than one domain.
>
> I don't understand that. I've got several domains' nameserver records
> pointed at my server, serving a number of protocols. But the server
> itself is in only one domain. Apache and Postfix and Bind all handle the
> different domains, but I think of all of them as virtual domains, not the
> one true domain that my server is part of.
>
> Am I thinking wrong? Or is it possible somehow for a machine to have 2 FQDNs?
> I've never considered that. And I can't think of how to configure things so
> 'hostname --fqdn' could answer with 2 strings...
The domainname that you set on a box has nothing to do with dns. Even
the hostname has nothing to do with dns. They're needed for
nis/nisplus/ldap and the hostname's useful in a shell prompt if you
ssh into more than one box; but that's it. Anything else is just
cosmetic.
If you're serving out http, email, or anything else, it's the dns
server(s)' entries that matter. You have to ensure that the hostname
and domainname held in dns match the apache/postfix/... config.
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