On 24-07-2012 22:17, Steve Holmes wrote:
Xymon 4.2.3. One of the DNS servers we monitor was down. The bbtest total time went from under 30 seconds to over 900 seconds almost all of which was for the DNS test.
This caused a number of problems. I removed the dns tag from the down server and the time dropped back to the normal level.
The mysteries to me are why did Xymon continue to test the DNS service on that server while the conn test was red? Why did it take 900 seconds for it to time out, even though I was running with --dns-timeout=60?
DNS timeout handling does not work correctly in versions prior to 4.3.8, it is a case of the DNS library (c-ares) not behaving the way I thought it did.
4.3.8+ has a workaround in place so the timeout is fixed at approximately 25 seconds. You can achieve almost the same result by running the old bbtest-net utility with "--dns-timeout=2" (no, this won't cause DNS lookups to timeout after 2 seconds).
And more importantly, is the behavior still the same in 4.3.9?
No.
Regards, Henrik