To prevent the monitor from incorrectly marking the server down, modify the health monitor Send String to send an HTTP 1.1 request by specifying the HTTP version, the required Host header, and the Connection: close header.
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: <space> suffices in most cases. A null value is valid unless the HTTP server requires them for virtual hosting.
For example:
Your existing monitor requests the default document in the root directory by sending the following Send String:
GET /
To send an HTTP 1.1 compliant request, modify the existing Send String to appear similar to one of the following examples, depending on your version:
10.2.0 and later
GET / HTTP/1.1\r\nHost: host.domain.com\r\nConnection: Close\r\n\r\n
or
GET / HTTP/1.1\r\nHost: \r\nConnection: Close\r\n\r\n
9.4.x, 9.6.x, 10.0.x and 10.1.x
GET / HTTP/1.1\r\nHost: host.domain.com\r\nConnection: Close
or
GET / HTTP/1.1\r\nHost: \r\nConnection: Close
9.2.x and 9.3.x
GET / HTTP/1.1\r\nHost: host.domain.com\r\nConnection: Close\r\n
or
GET / HTTP/1.1\r\nHost: \r\nConnection: Close\r\n
9.0.x and 9.1.x
GET / HTTP/1.1\nHost: host.domain.com\nConnection: Close\n
or
GET / HTTP/1.1\nHost: \nConnection: Close\n
4.x
GET / HTTP/1.1\nHost: host.domain.com\nConnection: Close\n
or
GET / HTTP/1.1\nHost: \nConnection: Close\n
Original instruction located at http://support.f5.com/kb/en-us/solutions/public/3000/200/sol3224.html
