Default HTTP/HTTPS monitor acceptable HTTP status codes?

Question

Hello,&nbsp;
I've been digging through F5's LTM documentation, but I am not able to find anything solid on the default acceptable HTTP/HTTPS monitor status codes. What is the LTM expecting back using the default HTTP/HTTPS monitors from the servers residing in a pool or directly associated with the node?&nbsp;
Thank you,
John&nbsp;

kevin_stewart · Answer

I'm pretty sure that ANY HTTP response is enough to keep the monitor up. &nbsp;

theo_12742 · Answer

While it's not well documented, the HTTP monitor will accept any response (including 302's). However, you can control this behavior by using RegEx in the Receive String. For example, I use the following (and use HTTP &gt;= 1.0):&nbsp;^HTTP.1\.[0|1]\s([2|3][0-9][0-9])Which marks the monitor as up for any HTTP code 200-399.&nbsp;

john4665f5 · Answer

Hello Theo,

Thank you for the response. I've tested a 302 response and the node was marked down, but a 301 works just fine. I didn't get a chance to look further into like the bigd debugs, but I wonder if it was because the response was "302 Found" instead of a typical 302 temporary redirect.

Just to clarify the reason for this question is not how to make the node available, I can modify the send/recv strings in a child monitor to pass the host header, 302, etc. and mark it up, but just curious as to what the default expected responses are.

Thank you,
John

kevin_stewart · Answer

At a minimum the default HTTP monitor send string is too simple. Change it to the following more specific string and you should see a difference:
GET /redir.php HTTP/1.1
Host: foo

Obviously change the URI as required.

theo_12742 · Answer

If that's the case, then I'll point you to the LTM monitors reference (https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-monitors-reference-11-5-0/3.htmlunique_475041279):

"Note: If you do not specify both a Send String and a Receive String, the monitor performs a simple service check and connect only."

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Default HTTP/HTTPS monitor acceptable HTTP status codes?

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