You have configured ACS to perform machine authentication against Active Directory. Both ACS and Active Directory hosts

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You have configured ACS to perform machine authentication against Active Directory. Both ACS and Active Directory hosts can ping each other, there is no firewall between them, and ACS trusts the correct CA. Yet the clients that are performing machine authentication with EAP-TLS and using valid certificates are failing to authenticate. What might the reason be?

A. The wrong UDP port for Active Directory is configured on ACS.
B. Machine access restrictions is enabled on ACS.
C. The client certificate key is less than 2048 bit.
D. The wrong date and time are on the ACS server.
E. The host is not configured in the ACS internal database.