DNS: Question about setting abc.com record
Daniel B. Thurman
dant at cdkkt.com
Wed Jun 18 16:52:13 UTC 2008
Howard Wilkinson wrote:
> 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.
>
Ok, thanks for this information! I was not sure what was going
on and why. I will look into sendmail to see what is going on.
Thanks for your help!
Dan
P.S. I noticed that you have email receipt requests turned on and
if that was intended, never mind.
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