RDNS Help

Discussion in 'Windows Small Business Server' started by GoodwinM, Jul 18, 2007.

  1. GoodwinM

    GoodwinM Guest

    I have installed a new SBS 2003 R2, standard server.

    Everything except some outgoing emails appears to be working fine. I am
    pretty sure I need to configure a Reverse DNS lookup, but have no clue on how
    to go about doing that.

    NSLookup returns the correct IP and server name (mail.domain.com), but there
    is no such thing as mail.domain.com configured and I am clueless on how to
    get this setup.

    Not real sure at this point even what information to include in this post,
    so if someone could please point me in the right direction, I could then get
    some sleep.

    Thanks
     
    GoodwinM, Jul 18, 2007
    #1
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  2. GoodwinM

    Robin Wenham Guest

    Setting up rDNS enables a receiving e-mail server who has your IP address to
    see what domain name it resolves to. This is used to help prevent spam and
    AOL in particular do not accept messages from e-mail servers where the rDNS
    resolved to a "generic" one (which will usually be the case if you have not
    set up a specific rDNS).

    You have two solutions: one is to send from your SBS to the outgoing SMTP
    server provided by your ISP (this is called using a Smart Host in SBS
    parlance). They will have an rDNS entry for their server.

    Or to set up an rDNS you need to contact your ISP: they need to set this up.
    There is nothing that you need to do on your server.

    Hope that helps.
     
    Robin Wenham, Jul 18, 2007
    #2
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  3. GoodwinM

    GoodwinM Guest

    Thanks for the response -

    I should have stated that this is using DNS and SMTP to send/receive mail.

    I need to setup the reverse dns lookup entries, but do not know how, step by
    step, to do that.
     
    GoodwinM, Jul 18, 2007
    #3
  4. GoodwinM

    Steve Guest

    As Robin says you can't setup the RDNS yourself-you have to have your ISP
    (which "owns" the IP address) do that. As he also says you can use your
    ISP's mail server as a smart host instead of DNS.
     
    Steve, Jul 18, 2007
    #4
  5. GoodwinM

    GoodwinM Guest

    I sort of understand what you are saying, but how do I explain this:

    This was on SBS 2000 and ran fine. Now it is on SBS 2003 and no longer
    works. The IP address is the same as before
    The domain name is the same as before

    It appears to me that I am missing a step somewhere, your thoughts?
     
    GoodwinM, Jul 18, 2007
    #5
  6. GoodwinM

    Robin Wenham Guest

    Outgoing and incoming e-mail are different scenarios - for the purposes of
    this discussion you should ignore incoming mail and concentrate on outgoing.
    All outgoing mail is sent with SMTP whether you use Smart Host or Direct
    Delivery.

    Without knowing the reason for it working on 2k, we can't comment but I
    suspect that you were using Smart Host for outgoing mail.

    Is there a reason that you want to persist with Direct Delivery (i.e.
    sending mail direct to the recipient's mail server) rather than switch to
    Smart Host?

    DNS is the linking of the domain name to your IP address: this is not
    reversible.

    rDNS is the linking of your IP address to a domain name: it does not have to
    be the same as the domain name used for DNS (although it would be sensible
    to use the same name) and is also not reversible.

    But if you still need to set up the rDNS then this *has* to be set up by
    your ISP. Contact their support department and tell them that you want to
    set up Reverse DNS on your IP address and tell them what name you want to
    you use: the same as your incoming mail server address would seem sensible.
     
    Robin Wenham, Jul 19, 2007
    #6
  7. GoodwinM

    GoodwinM Guest

    I am just not getting this, so please let me try again. Perhaps I am not
    smart enough to ask the correct question, so -

    Incoming mail is working fine, and I am not concerned with that.
    Outgoing mail is also working fine, except for some domains.

    I ran a report on DNSstuff.com and it indicates everything appears to have
    passed, except the following warning makes me think this is where the problem
    lies:

    "...mailbox server is claiming to be a host other than what it is...
    'mail.domain.com' claims to be host 'domain.com'... "

    Yesterday I ran the same report and it also indicated a problem with the
    Reverse DNS entries, today that part passes.

    Thanks in advance for any guidance. Please be gentle, I am trying to learn!
     
    GoodwinM, Jul 20, 2007
    #7
  8. GoodwinM

    GoodwinM Guest

    OK, I finally got this all working, and it had nothing to do with the ISP,
    there was a missing record on the local server that once added allowed the
    RDNS and correct identity of the mail.domain.com server to work properly.
     
    GoodwinM, Jul 21, 2007
    #8
  9. GoodwinM

    Robin Wenham Guest

    Glad that you got it working - for reference, where and what (as far as you
    are able) was the missing record?
     
    Robin Wenham, Jul 22, 2007
    #9
  10. GoodwinM

    GoodwinM Guest

    It was what I had thought in the beginning. I just struggled for a long time
    to get it to work. It may not be correct, or pretty, but it seems to be
    working now.

    I certainly do not know why this works, but it does. The domain.com host MX
    record points to the external IP address (static) of the local router with a
    name of mail.domain.com

    The router is port forwarding to the local server. The local server, not
    being named mail.domain.com, would not resolve correctly for a rDNS lookup
    required by some domains to deliver mail.

    From the dnsstuff report, I could see that unless there was a record
    somewhere that would resolve to mail.domain.com, mail would be rejected since
    the local server was not mail.domain.com. I added a reverse lookup zone
    using the primary server name of mail.domain.com, added the NS of
    mail.domain.com, added a PTR record to the correct IP - restarted DNS, and it
    all started working.

    I would bet there is another, better, way to get this working and am
    certainly open to any suggestions but at least the client's mail is now
    flowing.

    Thanks for the reply
     
    GoodwinM, Jul 22, 2007
    #10
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