What can REST Callbacks detect?

The correct answer is that REST Callbacks can detect HTTP error statuses, specifically those with status codes of 400 and above. When an application makes a REST API call, it receives an HTTP response that includes a status code indicating the outcome of the request. Status codes in the 400 range, such as 404 (Not Found) or 401 (Unauthorized), signify client-side errors, while 500 range codes indicate server-side errors.

These callbacks are designed to provide feedback about the success or failure of the API's response, allowing developers to implement error handling or logging mechanisms in their applications effectively. By detecting these status codes, developers can appropriately respond to various scenarios, such as prompting users, retrying requests, or altering workflows based on specific error conditions.

Connection timeouts and server delays are more related to network behavior and response time but are not inherently captured as part of the HTTP status codes. Unauthorized access errors do fall under the umbrella of HTTP errors, but since the question specifies detecting errors generally in the form of status codes, this answer is more comprehensive and correct in context.