Symantec Endpoint has total 8 features that are divided into 4 components
1. Antivirus and Antispyware Protection ( Antivirus + Antispyware )
2.Proactive threat Protection ( Proactive Behaviour based scan + Application Control + Device control )
3. Netowkr threat Protection ( Firewall + Intrusion Prevention System )
4. Symantec Network Access Control--which has to be purchased seperately
Once you have Install SNAC license on your SEPM on all the clients SNAC component will automatically get enabled and you cannot un-install or Disable it.
However it is harmless untill you configure it..
This is a policy based compliance products..which will check whatever policies you have configured whether the clients are compliant with it or not.
So without policy it just sits there..
Communication..
2 files were used in older version of symantec antivirus (10.x and earlier) namely grc.dat and root certificate.
From SEP 11..its only 1 file Sylink.xml, which will give you all the information about where this client belongs to. information in sylink are : server ip,port,domain id,communication mode, heartbeat interval etc..