HTTP Response with iRule

"I tried below iRule but it respond with 404 in both cases" This does not sound right. Note that the value of URI you're using in your conditional statement is HTTP path + Query. It's not the same thing as URL.

For your request, use the iRule below:

when HTTP_REQUEST {
  if {[HTTP::path] equals / }{
    HTTP::respond 404 content "HTTP ERROR 404 Reason:Not Found" Mime-Type "text/html"
    event disable
    TCP::close
  } elseif { [string tolower[HTTP::path]] starts_with /test }{
    return
  }
}