Dell IDRAC6 User Manual page 186

Ensure that you have uploaded the right Active Directory root CA
c
certificate to the iDRAC6 if you enabled certificate validation. Ensure
that the iDRAC6 time is within the valid period of the CA certificate.
If you are using the Extended Schema, ensure that the iDRAC6 Name
d
and iDRAC6 Domain Name match your Active Directory
environment configuration.
If you are using the Standard Schema, ensure that the Group Name
and Group Domain Name match your Active Directory configuration.
3 Check the domain controller SSL certificates to ensure that the iDRAC6
time is within the valid period of the certificate.
186
Using the iDRAC6 Directory Service