Re: [cobalt-users] DNS?

[Jeff Lasman <jblists@xxxxxxxxxxxxx>]

Neil Highley wrote:

>  Ref: RAQ 2
>  I have registered several domain names to one server, with one NIC,

To me a "NIC" means a Network Interface Card", or in other words, an
ethernet card, and your RaQ2 already has ethernet built in, so I presume
you mean something else.  Do you mean with one registrar?  Or with one
IP#?

> do I
>  still need to configure DNS (A,A,MX,PTR) for each site

Every site must have it's own DNS records.  Usually something like:

nobaloney.net.	IN	A	216.116.124.170
www		IN	A	216.116.124.170
mail		IN	A	216.116.124.170
nobaloney.net.	IN	MX	mail
ftp		IN	CNAME	www

You should NOT create PTR records unless your upstream has delegated
reverse DNS to you.  If your upstream has NOT delegated reverse DNS to
you, then your upstream needs to do your reverse DNS.

If your upstream HAS delegted reverse DNS to you, then your reverse DNS
should look something like:

216.116.124.170	IN	PTR	joshua.ez-access.com.

(The above is how we set up some of our records.)

> if I wish them to
>  have mailservers also?

If you're not going to use mailserver, either in or out, you may be
tempted to leve out the mail A record AND the MX record, but I wouldn't;
sometimes the server needs to send you email, and you'd like to be able
to get it, I'm sure.  You also may want to use the built-in Raq mailing
lists.

> How can I do a reverse lookup on virtual sites??

Keeping in mind what I wrote above about delegation for reverse DNS, one
other caveat to keep in mind is that an IP# should only resolve to ONE
actual name.  In general, it should resolve to the server's canonical
name, which in the case above is "joshua.ez-access.com" where "joshua"
is the hostname and "ez-access.com" is the domain name.

While some people will tell you that it must resolve to the same name as
each A record, or else mail (or something else) won't work, in a
nutshell, they are wrong.  For certain services to work correctly or at
all, IP#s must resolve, but to what is not defined.  Read the relevant
RFCs, or study the O'Reilly book "DNS and Bind" (or just believe me
<smile>).

Jeff
-- 
Jeff Lasman <jblists@xxxxxxxxxxxxx>
nobaloney.net
P. O. Box 52672
Riverside, CA  92517
voice: (909) 787-8589  *  fax: (909) 782-0205