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tnsping times intermittently high

From: Gerald Sinkiewicz <>
Date: Sun, 15 Jul 2007 02:01:11 GMT
Message-ID: <Hdfmi.19171$>

A bit strange:

  1. tnsnames.ora uses host = ipaddress, not FQDNS names.
  2. tnsping from the box (AIX5L) to one alias on the same box comes back at times OK (10msec) at other times OK (19000msec) or more. It was high for a period of a couple of hours, then the problem went away, well was still on-and-off at high numbers, but mostly OK (0msec).
  3. tnsping to other tns aliases on the same box did not show degraded performance at anytime.
  4. there are about 15 distinct listeners on the box (actually it is an HA cluster of 2 boxes but not RAC) each has its own IP address and distinct port number.
  5. Only one of the listeners is showing this degradation, all the others are consistenly 10msec.
  6. Eventhough there are no DNS names in the tnsnames.ora file, the problem seems to have come from a reverse dns lookup than oracle TNS was doing. We found the primary DNS was having a slow time doing a reverse lookup of just this one IP Address (this time). The secondary DNS was not slow for the same reverse lookup. We fixed the problem with the slow connections and tnsping high by swapping primary and secondary DNS's.
  7. A similar issue has occured with the same primary DNS a few weeks back but no Oracle related. The victum then was a couple of mail hubs.

So, why does tns do a reverse IP address lookup at all, it seems from our experience that it does?
Maybe it is for its listener.log or something like that? Or am I thinking incorrectly (again)? Received on Sat Jul 14 2007 - 21:01:11 CDT

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