Split-Brain DNS?

Discussion in 'Windows Small Business Server' started by Sorehead_5, Mar 6, 2008.

  1. Sorehead_5

    Sorehead_5 Guest

    We're having problems with mail delivery. The problem is apparently due to
    spam filtering methods now used by British Telecom and the fact that we lack
    a ptr record in our DNS. The company that provide our external DNS can't
    give us a ptr record because of the way that they've set up their system.
    So I figure the best solution is to have their records point to us as name
    servers, and set up our own DNS to resolve external queries.
    Am I off track? Is it feasible? Is it sensible? What would be the mechanics?
    SBS 2K3 Premium R2
    Sorehead_5, Mar 6, 2008
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  2. Sorehead_5

    Joe Guest

    Don't even think about it. Microsoft does not support the use of SBS for
    public DNS.

    The PTR record in question is that of your public IP address, and your
    ISP (*not* your domain DNS host, unless it happens to be the same
    company) must adjust it. And they most certainly can do it, because it's
    stored in their DNS server, and nobody else can.

    If they're not willing to set your PTR record according to your request,
    there's no conceivable way that they'd delegate the record to your own
    DNS server.
    Joe, Mar 6, 2008
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  3. If they don't give you a PTR record,
    And their excuse is because of they way they set up their system?

    This is probably not a ISP that does any Business Class Internet Service.

    To be Blunt, sounds like they don't know what the heck they are doing.
    If they claim they are "BUSINESS" ISP
    I'd call them and give them a Piece of my mind that's for sure.

    Any other ISP Options?



    Microsoft Gold Certified Partner
    Microsoft Certified Small Business Specialist.
    North America Remote SBS2003 Support - http://www.SBITS.Biz
    Introduction to Windows Small Business Server 2003 for Enterprise IT Pros

    Russ \(SBITS.Biz\), Mar 6, 2008
  4. PTR records are not the responsibility of your DNS provider (generally).
    They're the responsibility of your ISP (normally).

    All internet hosts are required to have a PTR by the RFCs, so any ISP not
    providing them should be shouted at.

    Not only should you have a PTR, but it should match at least one of the
    names that map to your IP address(es).

    So, if your DNS provider has:

    mail.yourdomain.com A

    in your DNS records, ideally the PTR for will be: PTR mail.yourdomain.com.
    Steve Foster [SBS MVP], Mar 6, 2008
  5. --

    Since this is England isn't that a Hanged, Drawn and Quartered punishment?


    I looked up what Hanged Drawn and Quatered was in Wikipedia

    1. Dragged on a hurdle (a wooden frame) to the place of execution. (This is
    one possible meaning of drawn.)
    2. Hanged by the neck for a short time or until almost dead. (hanged).
    3. Disembowelled and emasculated and the genitalia and entrails burned
    before the condemned's eyes
    4. Beheaded and the body divided into four parts (quartered).

    Ok A little harse but Really?
    They can't create a PTR record???
    Russ \(SBITS.Biz\), Mar 6, 2008
  6. Sorehead_5

    Joe Guest

    He mentions BT in connection with email, so BT is probably his ISP as well.

    They've run domestic telephones for a century, it will take them a while
    to get the hang of the Internet. They're certainly complete rubbish as a
    business ISP.
    Joe, Mar 6, 2008
  7. Sorehead_5

    Sorehead_5 Guest

    Thanks for all your responses.
    The hosts/registar who hold my records at the moment will allow me to change
    my A record and a glue domain to provide MX records on their DNS. Or they
    give the option simply to point to a new nameserver, which is where the idea
    came from. I had a lengthy chat about PTR records with them but they were
    adament that there was nothing they could do on that score. And yes, they're
    a big company, 1and1.
    I'm using BT (the ISP) as a smart host and THEY'RE bouncing anything that I
    auto-forward through the exchange server to an external address. If I route
    via DNS then the rest of the company mail becomes unreliable.
    It's an issue for me because it's an issue for the boss :-(
    I think I'll shelve the Split-brain then, and have a serious think about
    changing hosting company.
    Thanks again for all the replies.
    Sorehead_5, Mar 6, 2008
  8. Russ \(SBITS.Biz\), Mar 6, 2008
  9. split brain (it's actually 'split horizon', unless you are 15 and hang out
    in 133t *nix groups) DNS will not deal with the issue of your pointer

    When querying a PTR record the query is sent to the owner of the IP block,
    in this case BT.

    In relation to mail it's a two stage process. The IP's of 'responsible mail
    servers' are 1st resolved and then the owner(s) of these IP addresses is
    queried for PTRs.
    SuperGumby [SBS MVP], Mar 7, 2008
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