How to check if a RDP client uses NLA to access a RDP host

Hello,

I have a 2008 R2 RDP Host, configured for negociate the authentication. I would like to monitor if clients are successfully able to negociate usage of NLA.

Note: I can't modify server config for now, is there an event log, or anything that would tell me when NLA is used for a given connection ?

Regards.