http code not found code example

Example 1: 200 error code

The HTTP 200 OK success status response code indicates that the request has succeeded. A 200 response is cacheable by default. The meaning of a success depends on the HTTP request method: GET : The resource has been fetched and is transmitted in the message body.

from developer.mozilla.org

Example 2: web http code for not found

Note: The existence of the 503 status code does not imply that a
      server must use it when becoming overloaded. Some servers may wish
      to simply refuse the connection.