What HTTP status codes do you know?

1xx - Informational: the request was received, and the process is continuing. 2xx - Success: the request was successfully received, understood, and accepted. 3xx - Redirection: further action is needed to complete the request. 4xx - Client Error: the request contains incorrect syntax or cannot be fulfilled. 5xx - Server Error: the server failed to fulfill an apparently valid request.

Most common:

• 200 OK: The request was successful.
• 201 Created: The request was successful, and a new resource was created.
• 204 No Content: The request was successful, but there is no content to return.
• 301 Moved Permanently: The resource has been permanently moved.
• 400 Bad Request: The server cannot process the request due to incorrect syntax.
• 401 Unauthorized: Authentication is required to access the resource.
• 403 Forbidden: The client does not have permission to access the content.
• 404 Not Found: The server cannot find the requested resource.
• 500 Internal Server Error: The server encountered an unexpected condition.
• 502 Bad Gateway: The server was acting as a gateway and received an invalid response from the upstream server.
• 503 Service Unavailable: The server is temporarily unavailable (due to overload or maintenance).