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  1. ZABBIX BUGS AND ISSUES
  2. ZBX-17396

Non-existing DNS entries in Server= increase Zabbix Agent response time

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    • Team D
    • Sprint 62 (Mar 2020)

    Description

      Steps to reproduce:

      1. Install Agent on Windows
      2. Try with correct DNS entries to get value from another machine:
        [[email protected]]# time zabbix_get -s 10.211.55.4 -k system.uname
        Windows VMZ 10.0.18363 Microsoft Windows 10 Pro x64
        
        real	0m0.052s
        user	0m0.003s
        sys	0m0.002s
        
      3. Try with incorrect DNS entries to get value from another machine (the more incorrect entries you have, the more time you need):
        Server=qwerty123,qwerty123,10.211.55.39 
        
        [[email protected]]# time zabbix_get -s 10.211.55.4 -k system.uname
        Windows VMZ 10.0.18363 Microsoft Windows 10 Pro x64
        
        real	0m2.312s
        user	0m0.003s
        sys	0m0.002s
        [[email protected]]# time zabbix_get -s 10.211.55.4 -k system.uname
        Windows VMZ 10.0.18363 Microsoft Windows 10 Pro x64
        
        real	0m4.640s
        user	0m0.001s
        sys	0m0.003s
        

      On Linux it's not a problem, since ncsd daemon will cache negative answers, but on Windows you can see errors like:

      Get value from agent failed: ZBX_TCP_READ() timed out
      

      By default, Windows stores positive responses in the DNS cache for 86,400 seconds (i.e., 1 day) and stores negative responses for 300 seconds (5 minutes).

      Expected:
      Do not fail with timeout with negative DNS in the Server= option.

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              mgeneralova Marina Generalova
              edgar.akhmetshin Edgar Akhmetshin
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                Updated:
                Resolved: