Ejemplo GET condicional
GET /picture/car.jpg HTTP/1.0
User-agent: Mozilla/4.0
HTTP/1.0 200 OK
Date: Wed, 4 Aug 2023 16:21:22
Server: Apache/1.3.0 (Unix)
Last-Modified: Mon, 2 Jul 2023 12:32:12
Content-Type: image/jpg(.......contenido del objeto.......)
GET /picture/car.jpg HTTP/1.0
User-agent: Mozilla/4.0
If-modified-since: Mon, 2 Jul 2023 12:32:12
HTTP/1.0 304 Not Modified
Date: Wed, 4 Aug 2023 18:35:11
Server: Apache/1.3.0 (Unix)(....... cuerpo vacío, sin contenido ........)
HTTP/1.0 200 OK
Date: Wed, 4 Aug 2023 18:35:11
Server: Apache/1.3.0 (Unix)
Last-Modified: Wed, 4 Aug 2023 17:59:43(....... contenido del objeto .......)
