At 10:34 AM -0600 11/16/02, Michael A. Pasek wrote:
In SIMS Digest #1853, Bill Cole <[EMAIL PROTECTED]> wrote:I wonder if it might not be because the reverse DNS for your mail server's IP address is bad? It seems to be returning a CNAME instead of a PTR, and the name in that CNAME does not resolve. That is wrong 2 ways. It should yield a PTR record pointing at a name that resolves, preferably back to the same IP.A CNAME for an IP address is the only way to do sub-delegation of address blocks on non-octet boundaries. See http://www.ietf.org/rfc/rfc2317.txt for the "accepted" way to do this. Of course, the CNAME should be able to be resolved to a PTR.Some mail servers these days reject connections from IP addresses without reverse DNS or without reverse DNS that seems 'proper' for various definitions of 'proper.' Arguably your IP address has no reverse DNS because it does not have a PTR record, and even if one accepts the CNAME record as an adequate alternative, the name provided in any CNAME should always resolve to an address.Um....I think in this case, you want the CNAME to resolve to a host name -- and THAT name should resolve to an address. If you've done it all correctly, it will be the same address that you started with. There are certainly MTAs that will not accept mail if the PTR record does not resolve to a hostname, and others that verify that the hostname resolves back to the same IP address. Still others (very few) will verify the forward and reverse lookups AND check to make sure that the name given in the HELO/EHLO greeting all match, as well. Normally, you would not be doing the sub-delegation (and using CNAME records) unless you're managing your own DNS. Talk to the ISP and have them fix this (it was probably set up for the previous owner of your address space, and never updated). Michael A. Pasek Pasek Consulting, Inc. 9741 Foley Boulevard NW Coon Rapids, MN 55433-5616 (612) 597-5977 [EMAIL PROTECTED] ############################################################# This message is sent to you because you are subscribed to the mailing list <[EMAIL PROTECTED]>. To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> To switch to the INDEX mode, E-mail to <[EMAIL PROTECTED]> Send administrative queries to <[EMAIL PROTECTED]>
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