Hello,
To display the list of unauthorized devices that the client detects:
1 In the console, click Home.
2 On the Home page, in the Security Status section, click More Details.
3 In the Security Status Details dialog box, scroll to the Unknown Device Failures table.
4 Close the dialog box.
Check these Articles:
Configuring a client to detect unmanaged devices
http://www.symantec.com/docs/HOWTO80763
What does it mean to set a client as an Unmanaged Detector?
http://www.symantec.com/docs/TECH183746
Find Unmanaged Clients on a remote network location using the Unmanaged Detector
http://www.symantec.com/docs/TECH96234
Unmanaged Detector in SEP 12.1
https://www-secure.symantec.com/connect/articles/unmanaged-detector-sep-121
Check this Thread:
https://www-secure.symantec.com/connect/forums/how-unmanaged-detector-works
Hope that helps!!