Re: DNS: Question about setting abc.com record

Daniel B. Thurman wrote:

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@xxxxxxx 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@xxxxxxx" 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@xxxxxxx 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@xxxxxxx
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

The point I was making was that the address associated with the '@' record is independent of the name server information. The name server address data is correctly listed later in the file. Thus you could if you did not have any other services list the name servers without that record.

Your email SHOULD be delivered using the MX records data. Which again is independent from the '@' address record. I say SHOULD because you may have a mail routing issues depending on the mailer you use and how it it configured. Sendmail can be set up so that it will deliver locally even in the presence of relevant MX records. This has been the default in some distributions. I do not know about the current Fedora set up as we use custom configurations for all of our systems.

So I suspect you need to look at the mailer set up not the address record entries in the DNS arena.

Howard.

P.S. I have copied this back to the mailing list, but I suspect we have broken the thread.