Resolving mail server name internally and externally

Discussion in 'DNS Server' started by UNIX, Apr 3, 2008.

  1. UNIX

    UNIX Guest

    Hi all,
    I'll try to keep this short, but I'm hoping I've got the answer right
    already and just need some help applying the solution.

    I have a client with an SBS2003 R2 server, and we are running several email
    domains on it for them. Because of this, I have created additional POP
    accounts on some Outlook clients as a solution for them to be able to 'Send
    As' multiple email addresses/business names.

    This all works just fine (It even allows them to use multiple Signatures,
    just like in Outlook Express), EXCEPT, when they are plugged into the Local
    Network/Domain, and the DNS server is pointing to the SBS Server (as it
    should), it still resolves 'mail.theirdomain.com' to the external IP address
    of their internet connection.

    This is fine when they ARE external to the network, as it seems to send
    through the Exchange server whilst 'Out and about' no worries. Whilst on the
    LAN though, I get a 'Could not connect to SMTP server' error.

    I think this is because it is trying to go 'OUT' the internet connection,
    then 'BACK IN', because it resolves the (mailserver) name to the internet
    connections Permanent IP address.

    I'm think all I need to do is configure the DNS server on the SBS server so
    that when the Client PC requests 'mail.theirdomain.com' to be resolved on
    the LAN, it gets the LOCAL IP address of the SBS server returned to it.

    Problem is, I don't know how to add this record properly to the SBS server.

    I'm pretty sure I need to add a 'Forward Zone' for the external email domain
    name, then an 'A' record for 'mail', but I don't want to screw the rest of
    the DNS server 'guessing' at how to do this.

    Do you just run through the 'Add Forwarder Zone' wizard which you activate
    from the 'Action' menu, or is there some other way to do it?

    I read somewhere that you could do this in DHCP instead? - Or am I
    completely barking up the wrong tree here?

    Sorry about the long-windedness!

    Thanks in advance
    Scott
     
    UNIX, Apr 3, 2008
    #1
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  2. Yes, that's right. Just create the zone and add an entry for the mail server
    with the internal address.
    Anthony,
    http://www.airdesk.co.uk
     
    Anthony [MVP], Apr 3, 2008
    #2
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  3. UNIX

    UNIX Guest

    Thanks Anthony.

    Jsut had a look at the wizard, and the first thing it asks is whether I
    want to create a Primary, Secondary or Stub zone. I'm pretty sure this
    'mail' A record is the only one I'm (ever?) going to be adding, so which of
    the three types should I be creating?

    Cheers!
    Scott
     
    UNIX, Apr 3, 2008
    #3
  4. Read inline please.

    In
    I don't know what is going on with my OE mail reader, I posted the step by
    step early this morning, and it isn't here yet.

    You need a Primary (Store in Active Directory is fine), name the zone
    mail.theirdomain.com, Then in this zone create one new Host (A) record,
    leave the name field blank, and give it the internal IP of the mail server.
    This prevents you from having to add records for other hosts in
    theirdomain.com, your server becomes authoritative for mail.theirdomain.com,
    the rest of theirdomain.com is forwarded.




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    Kevin D. Goodknecht Sr. [MVP]
    Hope This Helps

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    Kevin D. Goodknecht Sr. [MVP], Apr 4, 2008
    #4
  5. UNIX

    UNIX Guest

    Thanks Kevin,
    I had actually already added a 'primary' (Stored in AD) for
    'theirdomain.com.au', and added an A record for 'mail'. This works fine now,
    but I can see where you'er coming from with the way you've described to do
    it.

    I thought a consequence of doing it the way I have would be that from
    'inside' the network, they would no longer be able to browse to their
    (externally hosted) website at 'www.theirdomain.com' - but I just tested
    it - and they can?

    I can only assume that this is because I haven't added a www. record, so I
    should be OK to leave it as-is?

    Thanks again for your help guys - much appreciated.

    Scott
     
    UNIX, Apr 4, 2008
    #5
  6. Kevin's is the smart way to do it when the domain DNS is hosted externally
    and you just have one record to vary.
    Otherwise, if you want a different DNS response than the one you get from
    the authoritative (external) DNS server, you need to maintain your own copy
    of the zone, complete with same and different records. You would need a
    record for both mail and www.
    Anthony,
    http://www.airdesk.co.uk
     
    Anthony [MVP], Apr 4, 2008
    #6
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