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EK1113_231252's avatar
EK1113_231252
Icon for Nimbostratus rankNimbostratus
Nov 08, 2017

About HTTP monitor

Hello All,

 

I use the Get method in the health check.

 

However, the health monitor was green when the server was down. Has a similar event occurred?

 

Parameters: GET /lbchk/apchk.asp （Other settings default setting）

 

Using windows server2008 IIS7.0 It was ESTABLISHED if check netstat on server.

 

It is assumed that the session remains and the health check does not operate normally.

 

BIG-IP
devops
LTM
  • Lee_Sutcliffe's avatar
    Lee_Sutcliffe
    Icon for Nacreous rankNacreous
    Nov 08, 2017

    Have you verified that the server in question is configured with the correct IP and port in the pool where the monitor is applied?

     

    If the server is down (i.e. switched off) the monitor would not receive a response. Or do you have any other monitors applied to the pool, such as gateway_icmp which may still give a response when the web service is down.

     

  • Gonzalex_330537's avatar
    Gonzalex_330537
    Icon for Cirrostratus rankCirrostratus
    Nov 08, 2017

    Are you using the default HTTP monitor or custom one? There is an option called "Reverse" which reverses the logic of the monitor. This option is off by default; so if you are using the default monitor, it shouldn't be an issue.

     

    What do you mean by "server down"? Do you mean, literally down; powered off? Maybe your server is up because the logic in your monitor is wrong.

     

    • EK1113_231252's avatar
      EK1113_231252
      Icon for Nimbostratus rankNimbostratus
      Nov 08, 2017

      Sorry, The explanation was insufficient.

       

      For the pool, only applicable HTTPmonitor is applied. Also, "Reverse" is OFF.

       

      Normally, you can monitor the service normally Although I stopped IIS on the server at one time, the health check remained green.

       

      When I stopped the service of worldwideweb, we switched to red.

       

      Although IIS is down and there should not be a response from the server, an incomprehensible event occurred that became green.

       

      It is not reproducible and dumpFile at the time of event occurrence can not be obtained.

       

  • Jinshu's avatar
    Jinshu
    Icon for Cirrus rankCirrus
    Nov 08, 2017

    Hello,

     

    Depends on what 's your receive string configured.

     

    If you kept it as blank, F5 will mark server up unless thers's a time out. This means the application is down and giving you 404 or 500 error, still your pools will be active.

     

    You can change the recieve string to 200 OK so that F5 will mark pool member offline if the response is no 200 OK.

     

    Also check the status of your health monitor running curl from F5 if server is down and make sure that there are no surprises.

     

    curl -v http://yourserverip.com/lbchk/apchk.asp

     

    Hope this helps.

     

    -Jinshu