Solutions
Client lookup
Dynamic User Registration (DUR) will fail if no PTR record exists on the DNS server for the client machine. A reverse zone must be implemented for DUR to function correctly.
ASCII encoding is assumed for the DNS reverse lookup process. If a computer name uses a character set other than ASCII, DUR may fail for that machine.
Group check
If group check does not seem to be working as expected with DUR, verify whether the named groups are part of an Active Directory domain. Group checks work with Active Directory domain groups only. It will not work with local Windows groups.