SMTP & DNS Question
Version:
iPlanet Messaging Server 5.2 HotFix 2.14 (built Aug 8 2006)
libimta.dll 5.2 HotFix 2.14 (built 16:39:09, Aug 8 2006)
Microsoft Windows 2000 Professional version 5.0 Service Pack 4 (Build 2195)
Hi all,
A few days ago our smtp services slowed to a crawl; I could not telnet to port 25 from the server itself (connection refused). When I disabled the NIC smtp services returned and I could telnet into port 25 from the console and get the 220 response. This situation persisted for more than 20 hours (accompanied by frantic efforts to find and fix the problem) after which it cleared. My belief is that the DNS server was not doing recursive lookups and smtp was waiting for an answer that never came, tyeing up all threads. I wish I'd thought to test this during the crises, but I only did nslookup, non recursive, from the server to see if I could reach the DNS server; I could. The network & DNS people here believe that the problem is internal to the Messaging Server - a mangled query or not using the DNS server defined for the system, or . .
Below are snippets from some of the log files during the crises. I would like to know if my theory is a possible explanation; Would the smtp service wait for the recursive reply, tieing up all the treads? Is there a way to (temporarily) tell smtp to accept non authoritative answers? Does this entry of the tcp_local_master - ;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 - indicate that this is a reply, not a logging of the query (query bit set to 1)? Any ideas, thoughts, or suggestions will be appreciated.
Thanks,
Steve
mail.log_current
Failed MX lookup; try again later
tcp_local_slave.log
Invalid socket descriptor, status = -1
tcp_local_master
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2155
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;intonewhy.com, type = MX, class = IN
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2139
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;QUZUSOKO.phydam.info, type = MX, class = IN
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2123
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;melloexchange.com, type = MX, class = IN
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2123
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;;bounce.tainoncount.com, type = MX, class = IN
