Spam Filter ISP Support Forum

  New Posts New Posts RSS Feed - reverse dns PTR record points to Nameserver
  FAQ FAQ  Forum Search   Register Register  Login Login

reverse dns PTR record points to Nameserver

 Post Reply Post Reply
Author
russ View Drop Down
Guest Group
Guest Group
Post Options Post Options   Thanks (0) Thanks(0)   Quote russ Quote  Post ReplyReply Direct Link To This Post Topic: reverse dns PTR record points to Nameserver
    Posted: 29 April 2003 at 12:09pm

I've recently run into a situation where the reverse lookup failed on an incoming connection.

In looking into it, the sender was valid, although the MX records point to their internal nameservers. The PTR record for the incoming IP does not resolve by querying my DNS server, my forwarders, or the root servers. However, by querying one of the listed nameservers for the IP/MX record in question, there is a PTR record for the IP that points to one of their nameservers. Am I making any sense?

The host IP in question is 12.2.45.130 and belongs to a VERY large organization (Gates Arrow.)

FWIW, I use DNS Export Pro to perform zone lookups, etc.

I hesitate to disable the reverse lookup as it alone kills about half my spam per day. As it is now, I have to keep a close eye on the quarantine and I'm not in the shop all the time...I may decide to put the domain in question ion my white list but prefer not to if at all possible.

I've seen discussion that recommends admins remove their "direct" PTR-to-MX host records to reduce spam on their side. Seems to me that they would then see alot of undeliverables given the expanded use of tools like Spamfilter and others by us all.

Is Spamfilter prone to problems when dealing with complex zone records? Is the problem on their side? Is there a problem with *my* DNS lookups?

Thanks,

Russ

Back to Top
LogSat View Drop Down
Admin Group
Admin Group
Avatar

Joined: 25 January 2005
Location: United States
Status: Offline
Points: 4068
Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 29 April 2003 at 6:44pm

Russ,

We were not able to find a PTR record either. Without knowing what the domain (and thus its nameservers..) is, we cannot verify this, but here's a possible scenario. If you query their DNS server directly and see a PTR, but this record does not show using other DNS servers, it is possible that their upstream provider (AT&T ?) is not doing their in-addr reverse zone transfers correctly. It does not matter if they're a big company, we've seen major blunders by quite a few large companies who should have know better...!

Roberto Franceschetti
LogSat Software

Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.063 seconds.