401 Unauthorized - HTTP | MDN
This status is sent with a WWW-Authenticate header that contains information on how to authorize correctly. This status is similar to 403, but in this case, authentication is possible. Status 401 Unauthorized Example response HTTP/1.1 401 Unauthorized Date: Wed, 21 Oct 2015 07:28:00 GMT WWW-Authenticate: Basic realm="Access to staging site"
DA: 14 PA: 80 MOZ Rank: 23