3Com 5500-SI Configuration Manual page 641

Setting Up A RADIUS Server 641
Save the certificate using DER x.509 encoding, select DER encoded binary
followed by Next. Provide a name for the certificate and save it to a specified
location.
Click Finish and followed by OK.
t Exit the Certification Authority management tool and launch the Active
Directory Users and Computers management tool. Ensure that the Advanced
Features are enabled in the Action menu, as shown below.