Which authentication method involves passing a unique key with each request?

• A. Basic Authentication
• B. OAuth
• C. API Key
• D. Session-based Authentication

Answer: (C)

The authentication method that involves passing a unique key with each request is API Key authentication. In this approach, a unique key is assigned to a user, application, or client, which is then included in every request made to a server. This key serves as a means of identifying and authorizing the requester, allowing the server to verify that the request comes from a legitimate source.

API Key authentication is widely used in various web services and APIs to enhance security and control access to resources. By requiring the key to be sent with each request, it allows for easy tracking of usage, quota management, and provides a straightforward method for developers to authenticate requests without requiring complex protocols.

Other options entail different methods of authentication. Basic Authentication transmits credentials (username and password) inline with requests, while OAuth is a more complex framework that allows third-party services to exchange secure tokens rather than simple keys. Session-based Authentication relies on stored session data on the server, using cookies to maintain state between the client and server, which differs from the stateless nature of API Key-based authentication.