Cisco IDS sensors form the eyes and ears of your Cisco network intrusion detection system. Placing sensors correctly throughout your network is crucial to successfully implementing your Cisco intrusion detection system .Which two of these are characteristics of an IDS sensor？（）

A. has a permissive interface that is used to monitor networks
B. is an active device in the traffic path
C. passively listens to network traffic
D. has a promiscuous interface that is used to monitor the network