HTTP Codes

Question 1

100-199

Answer 1

Informational

Question 2

200-299

Answer 2

Successful

Question 3

300-399

Answer 3

Redirection

Question 4

400-499

Answer 4

Client error

Question 5

500-599

Answer 5

Server error

Question 6

200

Answer 6

OK

Everything worked as expected.

Seen on successful GET, POST, PUT, DELETE requests.

Question 7

201

Answer 7

Created

The server created a resource (commonly after POST).

Question 8

204

Answer 8

No Content

The request succeeded, but no response body is returned (often after DELETE or a successful update with no content to return).

Question 9

301

Answer 9

Moved Permanently

The URL of the requested resource has been changed permanently. The new URL is given in the response.

Question 10

302

Answer 10

Found

Temporary redirect; often shows up when testing login flows.

Question 11

304

Answer 11

Not Modified

Browser caching: tells the client to use its cached version.

Question 12

401

Answer 12

Unauthorized

Although the HTTP standard specifies “unauthorized”, semantically this response means “unauthenticated”. That is, the client must authenticate itself to get the requested response.

Question 12

400

Answer 12

Bad Request

The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

Question 13

403

Answer 13

Forbidden

The user is authenticated but not allowed to access the resource.

Question 14

409

Answer 14

Conflict

Happens when a request conflicts with the current state of the server (e.g., duplicate unique fields)

Question 14

404

Answer 14

Not Found

The server cannot find the requested resource. In the browser, this means the URL is not recognized. In an API, this can also mean that the endpoint is valid but the resource itself does not exist. Servers may also send this response instead of 403 Forbidden to hide the existence of a resource from an unauthorized client. This response code is probably the most well known due to its frequent occurrence on the web.

Question 15

422

Answer 15

Unprocessable Entity

Often from validation failures, especially in RESTful APIs.

Question 16

500

Answer 16

Internal Server Error

The server has encountered a situation it does not know how to handle. This error is generic, indicating that the server cannot find a more appropriate 5XX status code to respond with.

Question 17

502

Answer 17

Bad Gateway

This error response means that the server, while working as a gateway to get a response needed to handle the request, got an invalid response.

Question 18

503

Answer 18

Service Unavailable

The server is not ready to handle the request. Common causes are a server that is down for maintenance or that is overloaded. Note that together with this response, a user-friendly page explaining the problem should be sent. These temporary condition responses should usually not be cached.

Question 19

504

Answer 19

Gateway Timeout

This error response is given when the server is acting as a gateway and cannot get a response in time.