HTTP Health Monitor Failing, Not Sure Why

Question

I tried creating a custom http health monitor for one of our applications with a simple SEND and RECIEVE configuration. &nbsp;Send String: GET /application/URI/resource.ascx 
Receive String: HTTP/1.1 200 OK 
&nbsp;I switched the appropriate pool to use this new monitor and it marks the pool members down.&nbsp;I checked the web logs on these apps servers and I can see them responding to the LTM with a 200 OK.&nbsp;I also ran a curl from the LTM to test manually and I get the appropriate response: HTTP/1.1 200 OK&nbsp;I don't really know why it's not working, it seems like this should be the correct receieve string. &nbsp;Any idea's on something else to try?&nbsp;Thanks!

jaikumar_f5 · Accepted Answer

Can you make a simple change and let us know if it fixes,&nbsp;Send String: GET /application/URI/resource.ascx HTTP/1.1
Host: www.domain.com
Connection: Close

Receive String: "200 OK"&nbsp;

iaine · Answer

Hi&nbsp;You're not sending your request string as a HTTP/1.1 formatted string but you're receive string is looking for a 1.1 response - there' a great KB article on this - https://support.f5.com/csp/article/K2167 - that goes into great detail on http monitors with good examples.&nbsp;Also, you can enable logging on your monitor to understand what is happening, see https://support.f5.com/csp/article/K12531 for more info on how to do this

hamish · Answer

Generally that won't be an issue. Except for the HTTP/0.9 request... (i.e. A lot of servers will reply 1.1 if you ask them a 1.0 request - even if it is technically out of spec)Change your request to at least HTTP/1.0 i.e.GET /application/URI/resource HTTP/1.0

And make sure your server really does reply with HTTP/1.1 and not HTTP/1.0. if you do require an HTTP{/1.1 request you (should) have to add a few headers to make a real request. HTTP/1.1 made several of them 'mandatory'But like iaine said. Enable debug to see what is being compared. It's likely something small and 'obvious' once you've identified it

nick_greenfield · Answer

Thank you all for the suggestions, I am going to try this and let you know!

jaikumar_f5 · Answer

How did it go. Was this resolved.

nick_greenfield · Answer

Thank you all for the help, adding HTTP 1.1 and the Host: parameter fixed the issue.

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HTTP Health Monitor Failing, Not Sure Why

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