To authenticate with Cisco's DNA Center, which type of HTTP request method must be used?

PUT is used to update or replace a resource entirely, not for initial authentication.

PATCH is used to apply partial modifications to a resource, not for initial authentication.

GET is used to retrieve data from a specified resource, not for sending credentials to authenticate.

Cisco DNA Center's REST API, like many other RESTful APIs, uses the HTTP POST method for authentication, typically by sending user credentials in the request body to an authentication endpoint.

HEAD is similar to GET but only retrieves the response headers, not the body, and is not used for authentication.