How does https send string works ?

Happy to, chethan...

The Send String example you show sends an HTTP 1.1 request for the resource at URI /PasswordVault. The request includes an HTTP Host header (required for HTTP 1.1 requests) with value example.xyz.com, as well as a Connection: Close header to close the connection after the response is sent. The \r\n (carriage return/line feed) characters after the start line (GET /PasswordVault HTTP/1.1), at the end of each HTTP header, and at the end of all the headers satisfies HTTP RFQ requirements for HTTP request construction.

The Receive String indicates that if the exact text string 200 appears anywhere within the HTTP response (including status line and response headers), the response is considered successful and the system will mark the assigned BIG-IP resource (e.g. pool member or node) as available for traffic processing. The first place this string might appear is in the HTTP response code on the status line (e.g. 200 OK).

What I cannot tell is whether or not this test indicates actual application health. For that, I would have to know more about the application that is being delivered. But, based on monitor configuration requirements, it does the job.

Hope this helps.