A. The SDM QoS wizard will create two real-time traffic classes to handle VoIP and voice signaling packets.
B. The SDM QoS wizard will create three real-time traffic classes to handle VoIP， voice signaling， and video packets.
C. The SDM QoS wizard will create four real-time traffic classes to handle VoIP， voice signaling， video， and video streaming packets.
D. The SDM QoS wizard will create two business-critical traffic classes to handle transactional and network management packets.
E. The SDM QoS wizard will create three business-critical traffic classes to handle transactional， network management， and routing packets.
F. The SDM QoS wizard will create four business-critical traffic classes to handle transactional， network management， routing， and best-effort packets.

A. A class can be identified as a single application， multiple applications with similar service needs， or be based on the source or destination IP addresses.
B. A drawback of the DiffServ model is that it does not provide backward compatibility with devices that can only use the ToS field.
C. DiffServ uses the DiffServ field in the MAC header to mark frames into behavior aggregates （BAs）. 
D. The DiffServ field occupies the same eight bits of the MAC header that were previously used for the ToS field.
E. The first six high-order bits of the DiffServ field are used to identify the Resource Reservation Protocol （RSVP） value.
F. The primary goal of DiffServ is scalability.