HTTP/1.1 request MUST send a Host header.

important that all implementations of HTTP (including updates to existing HTTP/1.0 applications) correctly implement these requirements:   - Both clients and servers MUST support the Host request-header.

  - A client that sends an HTTP/1.1 request MUST send a Host header.

  - Servers MUST report a 400 (Bad Request) error if an HTTP/1.1

  request does not include a Host request-header.