DNS: Question about setting abc.com record

Daniel B. Thurman dant at cdkkt.com
Wed Jun 18 16:11:10 UTC 2008


Howard Wilkinson wrote:
>
> Daniel B. Thurman wrote:
> >
> > I have several DNS servers and wondered if the following
> > record entry is properly set for all of my DNS servers:
> >
> > $TTL 172800
> > @        IN SOA ns1.abc.com. admin.abc.com. (
> >                1               ; serial
> >                3H            ; refresh
> >                15M          ; retry
> >                1W            ; expiry
> >                1D )           ; minimum
> > ;============ Nameserver ================
> > @               IN NS           ns1.abc.com.
> > @               IN NS           ns2.abc.com.
> > @               IN NS           ns3.abc.com.
> > ;============ Mail Exchange =============
> > @               IN MX   10      mail1.abc.com.
> > @               IN MX   20      mail2.abc.com.
> > @               IN MX   30      mail3.abc.com.
> > @               IN TXT          v=spf1 a mx -all
> > ;============ Hosts ======================
> > @               IN A            10.1.0.1
> > mail1           IN A            10.1.0.1
> > mail2           IN A            10.1.0.2
> > mail3           IN A            10.1.0.3
> > ns1             IN A            10.1.0.1
> > ns2             IN A            10.1.0.2
> > ns3             IN A            10.1.0.2
> > ;========================================
> >
> > In particular, I am focusing on record:
> > @               IN A            10.1.0.1
> >
> > The reason I have set all of my DNS zones for the above record
> > for all of my DNS servers is because if had I set this record for the
> > actual localhost IP address, it appears that if I send mail on the
> > localhost, the localhost would receive the email I sent. For example,
> > sending mail to: joe at abc.com would be received at the localhost instead
> > of being sent to mail{1,2,3}.abc.com.  Worse, any localhost programs
> > attempting to send emails to "root at abc.com" would fail to be delivered
> > to one of the MX list.
> >
> > So, the question is, must each DNS server have it's own real IP address
> > in the '@' record?  If so, how do I get around this?
> >
> > Kind regards,
> > Dan
> >
> Dan,
>
> do you have any other services with the network address 10.1.0.1 which
> you want to refer to as 'abc.com'? If not you do not need the 'A' record
> just after the Hosts line. Otherwise for a simple internal network this
> look reasonable. However, do you not have any other hosts you need to
> address? If so the you need their 'A' records.
>
> Howard.
>
Yes, I have services at 10.1.0.1 as well as at several other
hosts.  The main reason that I use the @ is so that I can
use 'abc.com' such as dan at abc.com or to simply type
abc.com in the web-browser's URL line and it would get
resolved.

What I found was, if I was at host one.abc.com, which had
a DNS server and had @ record set to it's own IP address,
and a local account "dan", sending mail to dan at abc.com
would be received locally instead of being delivered
according to the MX records.  That is why I set the @
record for all of my DNS servers to the same IP address
and not to each DNS servers actual IP address.

Does this make sense?

Thanks!
Dan

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