Solutions :-
- Open The SEPM (Symantec Endpoint Protection Manager) Console.
- GO to Client TAB and click on My Company the Go to Client.
- Click On Find Unmanaged Computer.
- Slecte your network IP Address Rang.
If you have a Workgroup machines type * on are colon.
If you have Domain slecte the Domain and enter the Domain name user name and password.
And click on search Now
Your Without Symantec AV client show on Unknown Computers.
I have also attached the file for find the without AV client.
I think your problem will be resolve.