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HTTP Header
Host
RequestSpecifies the domain name of the server and optional port number.
HTTP header reference, syntax, examples, and developer usage.
What is the Host header?
The Host HTTP header is used to transmit metadata between a client and server as part of HTTP requests or responses.
HTTP headers define how content should be interpreted, cached, authenticated, secured, or processed by browsers and APIs.
Direction
This is a request header sent by the client to the server.
Syntax
Host: domain.com
Example
Host: api.example.com
Common use cases
- Virtual hosting
- Routing requests to the correct site
- Required header in HTTP/1.1 requests
Common mistakes
- Using the header in the wrong request or response context
- Sending invalid header values
- Incorrect header syntax
- Assuming the header automatically changes server behaviour