Details

      Description

      I have configured agentd to connect to the Zabbix server by using a hostname, instead of an IP. It seams to me that for every item queried, gethostbyname() is called.

      192.168.1.15 - DNS server in /etc/resolv.conf
      192.168.1.13 - Host where the agent is running
      zabbix.elabsis.com - Zabbix server

      tcpdump sample from the 192.168.1.13:

      17:12:15.075198 IP 192.168.1.15.53 > 192.168.1.13.46016: 25749* 1/2/2 A[|domain]
      17:12:15.083781 IP 192.168.1.13.45727 > 192.168.1.15.53: 14928+ A? zabbix.elabsis.com. (36)
      17:12:15.084509 IP 192.168.1.15.53 > 192.168.1.13.45727: 14928* 1/2/2 A[|domain]
      17:12:15.153713 IP 192.168.1.13.42149 > 192.168.1.15.53: 8538+ A? zabbix.elabsis.com. (36)
      17:12:15.154379 IP 192.168.1.15.53 > 192.168.1.13.42149: 8538* 1/2/2 A[|domain]
      17:12:15.172920 IP 192.168.1.13.47295 > 192.168.1.15.53: 19772+ A? zabbix.elabsis.com. (36)
      17:12:15.173582 IP 192.168.1.15.53 > 192.168.1.13.47295: 19772* 1/2/2 A[|domain]
      17:12:16.371257 IP 192.168.1.13.33089 > 192.168.1.15.53: 48187+ A? zabbix.elabsis.com. (36)
      17:12:16.371979 IP 192.168.1.15.53 > 192.168.1.13.33089: 48187* 1/2/2 A[|domain]
      17:12:16.374865 IP 192.168.1.13.36497 > 192.168.1.15.53: 9540+ A? zabbix.elabsis.com. (36)
      17:12:16.375738 IP 192.168.1.15.53 > 192.168.1.13.36497: 9540* 1/2/2 A[|domain]
      17:12:16.434436 IP 192.168.1.13.43697 > 192.168.1.15.53: 12163+ A? zabbix.elabsis.com. (36)
      17:12:16.435174 IP 192.168.1.15.53 > 192.168.1.13.43697: 12163* 1/2/2 A[|domain]
      17:12:17.662556 IP 192.168.1.13.43674 > 192.168.1.15.53: 50570+ A? zabbix.elabsis.com. (36)
      17:12:17.663198 IP 192.168.1.15.53 > 192.168.1.13.43674: 50570* 1/2/2 A[|domain]
      17:12:17.684247 IP 192.168.1.13.42368 > 192.168.1.15.53: 9102+ A? zabbix.elabsis.com. (36)
      17:12:17.684994 IP 192.168.1.15.53 > 192.168.1.13.42368: 9102* 1/2/2 A[|domain]
      17:12:17.698499 IP 192.168.1.13.60401 > 192.168.1.15.53: 960+ A? zabbix.elabsis.com. (36)
      17:12:17.699178 IP 192.168.1.15.53 > 192.168.1.13.60401: 960* 1/2/2 A[|domain]
      17:12:17.727855 IP 192.168.1.13.51960 > 192.168.1.15.53: 8929+ A? zabbix.elabsis.com. (36)
      17:12:17.728542 IP 192.168.1.15.53 > 192.168.1.13.51960: 8929* 1/2/2 A[|domain]
      17:12:17.751009 IP 192.168.1.13.38707 > 192.168.1.15.53: 10705+ A? zabbix.elabsis.com. (36)
      17:12:17.751738 IP 192.168.1.15.53 > 192.168.1.13.38707: 10705* 1/2/2 A[|domain]
      17:12:18.916101 IP 192.168.1.13.38377 > 192.168.1.15.53: 33673+ A? zabbix.elabsis.com. (36)
      17:12:18.916865 IP 192.168.1.15.53 > 192.168.1.13.38377: 33673* 1/2/2 A[|domain]
      17:12:19.976746 IP 192.168.1.13.52731 > 192.168.1.15.53: 37538+ A? zabbix.elabsis.com. (36)
      17:12:19.977385 IP 192.168.1.15.53 > 192.168.1.13.52731: 37538* 1/2/2 A[|domain]
      17:12:20.007473 IP 192.168.1.13.49112 > 192.168.1.15.53: 1608+ A? zabbix.elabsis.com. (36)
      17:12:20.008169 IP 192.168.1.15.53 > 192.168.1.13.49112: 1608* 1/2/2 A[|domain]
      17:12:20.054203 IP 192.168.1.13.56993 > 192.168.1.15.53: 36012+ A? zabbix.elabsis.com. (36)
      17:12:20.054905 IP 192.168.1.15.53 > 192.168.1.13.56993: 36012* 1/2/2 A[|domain]
      17:12:20.109898 IP 192.168.1.13.54451 > 192.168.1.15.53: 13610+ A? zabbix.elabsis.com. (36)
      17:12:20.110585 IP 192.168.1.15.53 > 192.168.1.13.54451: 13610* 1/2/2 A[|domain]
      17:12:20.194716 IP 192.168.1.13.34243 > 192.168.1.15.53: 14421+ A? zabbix.elabsis.com. (36)
      17:12:20.195350 IP 192.168.1.15.53 > 192.168.1.13.34243: 14421* 1/2/2 A[|domain]
      17:12:20.198975 IP 192.168.1.13.49746 > 192.168.1.15.53: 37948+ A? zabbix.elabsis.com. (36)
      17:12:20.199711 IP 192.168.1.15.53 > 192.168.1.13.49746: 37948* 1/2/2 A[|domain]
      17:12:20.271991 IP 192.168.1.13.43933 > 192.168.1.15.53: 60673+ A? zabbix.elabsis.com. (36)
      17:12:20.272650 IP 192.168.1.15.53 > 192.168.1.13.43933: 60673* 1/2/2 A[|domain]
      

      After adding a dozen hosts using the hostname of the server, my internal DNS server is being hammered by the same requests over and over.

      Using the IP address of the Zabbix server does not create any DNS traffic.

        Attachments

          Activity

            People

            • Assignee:
              Unassigned
              Reporter:
              miguelzinho Miguel Di Ciurcio Filho
            • Votes:
              12 Vote for this issue
              Watchers:
              13 Start watching this issue

              Dates

              • Created:
                Updated: