How is a SAML assertion delivered to Zscaler?

A SAML assertion is delivered to Zscaler by the Identity Provider (IdP) sending it through the user's browser to the Service Provider (SP). This method is part of the SAML authentication process, where once the user successfully authenticates with the IdP, the IdP generates a SAML assertion. This assertion is then transmitted to the SP (in this case, Zscaler) via a browser-based redirect or a POST request.

This browser-based flow is crucial as it ensures that the user's credentials are not directly sent to the SP, thus enhancing security. The assertion includes information about the user's identity and the authentication status, which the SP uses to grant access to resources.

Other methods mentioned in the choices involve different interactions that are not part of standard SAML workflows, emphasizing the uniqueness and importance of the browser involvement in the assertion delivery method.