Host

The Host request header specifies the host and port number of the server to which the request is being sent.

If no port is included, the default port for the service requested is implied (e.g., 443 for an HTTPS URL, and 80 for an HTTP URL).

A Host header field must be sent in all HTTP/1.1 request messages. A 400 (Bad Request) status code may be sent to any HTTP/1.1 request message that lacks or contains more than one Host header field.

Host: <host>:<port>

<host>

the domain name of the server (for virtual hosting).

<port> Optional

TCP port number on which the server is listening.

Host: developer.mozilla.org

• 400
• <base>