Re: [cobalt-users] DNS Setup on the RaQ3

[Jeff Lasman <jblists@xxxxxxxxxxxxx>]

jale@xxxxxxxxxx wrote:

> >A Record
> >domain.com -> IP address
> >www.domain.com -> IP address
> 
> Yes. And for each, check the box that says to do the reverse lookup (it is
> on the same dialog box as the one you are on at this point.

According to DNS specification (see the various DNS books or the RFCs)
you should only have one PTR record for each IP#.  Since the "reverse
lookup" checkbox will add one for every A record it's checked for you
should leave this unchecked for all A records except for one A record
per IP#.

> >Reverse PTR Record
> >IP address -> domain.com
> 
> No - you do not need to manually add ptr records, clicking the box in the
> section above will take care of what you need.

Additionally to my statement above, you should not do reverse (PTR)
records at all, either by checkbox or by Reverse PTR record unless your
upstream has delegated reverse DNS to you, and since most don't, the
best thing to do is ask them first.

What difference does it make if you have them and your upstream hasn't
delegated them to you?  Only this:  You'll have a false sense of
security as all reverse lookups using your nameserver will look good,
but reverse lookups from the rest of the world may fail, and you'll
waste a lot of time trying to find out why things don't work.

> >MX Record
> >(High) domain.com -> domain.com
> >(High) mail.domain.com -> domain.com
> >(High) www.domain.com -> domain.com
> 
> I use just one entry:
> domain.com -> www.domain.com
> Then in my email programs, the server for POP/SMTP is www.domain.com

You need an mx record for what may appear; on the left side of an email
address.  Since most people will get email at, for example,
address@xxxxxxxxxx, there should always be an mx record for domain.com;
it can point to any domain posted on the box that's got an a record
pointing to it; it doesn't have to be for the same domain, or for any
particular service.  domain.com can certainly point to domain.com, for
example.

If you look at the RaQ's virtusertable (/etc/virtusertable on the RaQ3,
as I recall, and /etc/mail/virtusertable on the RaQ4), you'll see that
all email that comes in for address@xxxxxxxxxx is first redirected to
address@xxxxxxxxxxxxxx, before delivery is made.

For this reason we should also have (for RaQ hosting, not for the
Internet in general), an mx record pointing www.domain.com somewhere;
again www.domain.com -> www.domain.com or www.domain.com -> domain.com
are both fine.

If you don't have an mx record for www.domain.com you'll probably NOT
have any problems; we were about three years into RaQ hosting before we
had the first problem occur; we learned <smile> to do it right.  Our
problem and my eventual solution are in the archives of this list.

Pop and SMTP can have their own A records, and if they do you can, but
don't have to, point your MX records to them; there's no real standard.

> You need your DNS server registered  - I use bulkregister.com; I'm pleased
> with them.

In general, only your domain registrar will register your nameserver; if
your domain is registered with networksolutions you'll have to register
your nameserver there as well.  Most registrars have a simple form to
fill out, or a website where you can do it.

Jeff
-- 
Jeff Lasman <jblists@xxxxxxxxxxxxx>
Linux and Cobalt/Sun/RaQ Consulting
nobaloney.net, P. O. Box 52672, Riverside, CA  92517
voice: +1 909 778-9980  *  fax: +1 909 548-9484