Exam ZDTE Topic 1 Question 48 Discussion

The ZIdentity documentation on external identity providers explains that Zscaler supports various third-party IdPs over SAML and OIDC, and then provides specific configuration guides for each provider. For PingOne, Auth0, and OneLogin, the ZIdentity help explicitly describes configuring each as an OpenID Provider (OP) for ZIdentity, clearly stating that they are used to provide SSO via OpenID Connect (OIDC).
By contrast, the ZIdentity guides for Microsoft AD FS consistently describe configuring AD FS "as the SAML Identity Provider (IdP) for ZIdentity," and the examples focus on SAML assertions, claim rules, and certificate bindings-not OIDC flows. In other words, AD FS is supported in a SAML mode with ZIdentity, but it is not listed among the IdPs configured as OpenID Providers for OIDC-based integrations.
The Digital Transformation Engineer identity modules reinforce this differentiation by mapping external IdPs to either OIDC or SAML in the ZIdentity configuration, and the hands-on labs use Azure/Microsoft Entra ID or PingOne for OIDC examples, while AD FS is shown only in SAML scenarios.
Therefore, among the options listed, Microsoft AD FS is the external IdP that is unsupported by OIDC with Zscaler ZIdentity, making option C the correct answer.