DNS: Question about setting abc.com record

[Howard Wilkinson]

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 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
>
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.


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