What Is Authenticate Preemptively

In general, preemptive authentication means that the server expects that the authorization credentials will be sent without providing the Unauthorized response. This reduces the load on network and the server itself. You can configure your requests to use or omit the preemptive authentication.

What is non preemptive authentication?

Objective. By Default non-preemptive authentication is used, which means that in the first step the request is sent without any authentication information. This is then replied with response 401 Unauthorized and a header with the required authentication information.

How do I authenticate a request?

A client that wants to authenticate itself with the server can then do so by including an Authorization request header with the credentials. Usually a client will present a password prompt to the user and will then issue the request including the correct Authorization header.