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cwkim_261931's avatar
cwkim_261931
Icon for Nimbostratus rankNimbostratus
Jul 31, 2018

HTTP monitor send string about "host"

Hi

 

I use the HTTP monitor like this... GET /A/B/C.html HTTP/1.1\r\nHost: \r\nConnection: close\r\n\r\n

 

Almost server's state is UP

 

But someone is DOWN...

 

And I modify the send string like this... GET /A/B/C.html \r\n\r\n

 

After modify it, server's state change UP!!

 

What is the reason that not set the "host" in send string.

 

Plz help me.

 

application delivery
BIG-IP
LTM
  • Filip_Mikulík_1's avatar
    Filip_Mikulík_1
    Icon for Cirrus rankCirrus
    Jul 31, 2018

    In HTTP v 1.1 is Host header mandatory. It is used for resolution destination web server (like the virtual host on apache, or server behind a reverse proxy,...).

     

    • cwkim_261931's avatar
      cwkim_261931
      Icon for Nimbostratus rankNimbostratus
      Jul 31, 2018

      I found this article.

       

      Note: HTTP/1.1 requires the Host header to be present in the request but does not require the header to contain a value. If you do not have a specific host name on your server, a value of Host: suffices in most cases. A null value is valid unless the HTTP server requires them for virtual hosting.

       

      (https://support.f5.com/csp/article/K3224)

       

      So, I want to know the reason of different result by using HOST and NULL HOST.