rDNS help

Discussion in 'Windows Small Business Server' started by Adam Butler, Apr 1, 2005.

  1. Adam Butler

    Adam Butler Guest

    My isp (SBC) has supposedly setup rdns back to my domain name which is the
    name of my SBS 2k3 server.
    I use exchange server and at times have trouble sending mail to certain mail
    servers due to no or improper ptr records.

    I have a true static IP to the public.

    I can't seem to get this to work.

    Do I need to open certain ports from the public side back into my 2k3 SBS
    box in order to get rDNS working correctly?

    Adam Butler, Apr 1, 2005
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  2. Reverse DNS (PTR records) is a feature of your ISP (SBC) DNS servers.
    Basically its out of your control.

    First of all, go to www.dnsstuff.com and put your public IP address on the
    Revers DNS lookup section. Then look in the answer section and see what name
    is associated with it. It should be something like

    If that's not the case you need to go to SBC and ask them to create a PTR
    record for your public IP that matches the MX record on your domain
    (whatever that is, but it should contain the name of your domain).

    Also, you might want to read this...
    Javier Gomez [SBS MVP], Apr 1, 2005
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  3. Adam Butler

    Bob Genestet Guest

    Yes, you need TCP port 25 incoming open to receive SMTP traffic. You can
    test your SMTP server from a command prompt using "telnet yourdomain.com 25"
    .. you will get an acknowledgement such as "220 yourdomain.com
    xxxxxxxxxxxxxxxx ready at certain certain date and time." Type QUIT to
    exit. It would be best to test from the outside from the internet, but will
    probably work inside.

    Bob Genestet, Apr 1, 2005
  4. Adam Butler

    Adam Butler Guest


    I did that and here is what I'm getting back from dnsstuff.com:

    Asking ns2.swbell.net. for PTR record:
    ns2.swbell.net [] says to go to kmissile.com. (zone:
    Asking kmissile.com. for PTR record: Error:
    kmissile.com [] reports a SERVER FAILURE.

    An error occurred: Server kmissile.com is reporting a server failure (it is
    probably broken).

    The results from dnsstuff.com have the correct public IP as well as server
    name but the "SERVER FAILURE" part is where I am stuck!

    Any idea why I see this SERVER FAILURE error when doing a rDNS lookup?

    I did alter the IP's as well as hostname here for security.


    Adam Butler, Apr 1, 2005
  5. Adam Butler

    Adam Butler Guest


    No problems receiving. Just sending to certain mail servers due to no rDNS
    on my public IP.
    Adam Butler, Apr 1, 2005
  6. Adam Butler

    Bob Genestet Guest

    Could be that your ISP won't allow you to send through their SMTP servers,
    their servers may view it a relay attempt. You might want to try using the
    smarthost setting in the internet connection wizard by entering your ISP's
    SMTP server name there.
    Bob Genestet, Apr 1, 2005
  7. Adam Butler

    Adam Butler Guest

    I'm sending from my own SMTP server.
    Nothing to do with my ISP and relaying!
    I can send to most anyone except for the ones that perform rdns lookup
    against my IP. AOL is a prime example.
    That is why I'm trying to get rdns setup.

    Adam Butler, Apr 1, 2005
  8. Adam Butler

    Bob Genestet Guest

    I did find this in at AOL
    a.. Reverse DNS must be in the form of a fully-qualified domain name -
    reverse DNS containing in-addr.arpa are not acceptable, as these are merely
    placeholders for a valid PTR record. Reverse DNS consisting only of IP
    addresses are also not acceptable, as they do not correctly establish the
    relationship between domain and IP address.

    Bob Genestet, Apr 1, 2005
  9. Adam Butler

    Adam Butler Guest


    That is exactly one of the places I go to test my setup.
    It is one that does not work for my IP!

    I think I may have messed up when I called SBC and asked them to setup rdns
    for me.
    They said something about delegating authority to myself.
    I don't know if this is really what I wanted them to do.

    From the tests I run, it looks like my public IP is supposed to be an actual
    public nameserver now.

    I need to do some more studying on this!

    Adam Butler, Apr 1, 2005
  10. Adam Butler

    Bob Genestet Guest


    I am using pure DNS with Exchange in SBS2003. My MX record points to my
    internet IP address provided by my ISP. I send using pure DNS through my ISP
    without Smarthost. I went here http://postmaster.aol.com/tools/rdns.html and
    tested my IP address and the test said it passed. My ip address resolved to
    my ISP's name as such - RDNS is: pppoe2684.rb.gh.centurytel.net
    Success! It appears you have Reverse DNS.
    I notice that I didn't have the in-addr.arpa place holder that is rejected
    by AOL.
    Unfortunately, we are dependent our ISP for how your rDNS is resolved by
    AOL. I am sorry that I cannot offer any more help...my knowledge of rDNS is
    rather finite.

    Bob Genestet, Apr 1, 2005
  11. Adam Butler

    Adam Butler Guest

    You know,

    Before I started messing with this, I had the same results as you get at the
    aol tools link.
    I actually think I was able to send mail to AOL users.
    I was just using AOL as an example.
    Now however when I run the AOL test, I get an error and it says I failed!
    I do know for a fact though that some ISP's mail servers rejected my
    exchange servers mail when sent directly.
    I'd have to send via my ISP's servers.
    The message returned back indicated it was due to rDNS problems.
    So that is why I ventured into the world of rDNS!!
    Some mail servers won't even send a failed message back so I'd never know
    that my mail failed. This is the main reason I wanted to setup rDNS
    I don't send much mail via my exchange server for this reason.

    My knowledge is also very limited on this subject!

    I'll either figure it out or simply ask SBC to put me back to the defaults.

    Adam Butler, Apr 1, 2005
  12. I think I may have messed up when I called SBC and asked them to setup
    Wow... if they did that you must own a lot of IP addresses. Never seen an
    ISP delegating just a couple of IPs.

    I suggest you contact them again and ask if they can host the PTR record for
    you. Tell them that you want: IN PTR
    mail.yourdomain.com. That should do the trick.

    If they cannot host your PTR records then you need to delegate the zone to a
    3rd party public DNS server (i.e. www.zoneedit.com) and create the PTR
    records there. I have never done this, but I know its possible.
    Javier Gomez [SBS MVP], Apr 1, 2005
  13. Reading the whole thread... this really looks like you asked SBC to delegate
    DNS zones to your server for your IP address block. Since your SBS box is
    not (and should not) act as a public DNS server then you don't get any
    answer. Please read my other posts below on how to fix this.

    Javier [SBS MVP]
    << SBS ROCKS !!! >>

    Javier Gomez [SBS MVP], Apr 1, 2005
  14. From these statement...
    I'm pretty sure that you asked SBC to do the wrong thing. You probably could
    send to AOL because the PTR record was working (maybe incorrectly
    configured, but at least there). If you asked them to delegate then the PTR
    record is not even resolvable.
    Javier Gomez [SBS MVP], Apr 1, 2005
  15. Adam Butler

    Adam Butler Guest


    Only 5 public IP's and I only use 2 of them!
    I will ask them to do what you suggest and if not then I'll ask them to just
    reset everything back to default.
    At least then I had a PTR record although it was not fully correct. It was
    better than nothing!
    Adam Butler, Apr 1, 2005
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