单项选择题
A.The ERX router sends an Active Discovery Offer message.
B.The ERX router sends an Active Discovery Initiation message.
C.The customer device sends an Active Discovery Offer message.
D.The customer device sends an Active Discovery Initiation message
单项选择题 A user is connected on a DSL line and is using a PPP over Ethernet service. Which network device encapsulates the datagram inside of an ATM header?（）
多项选择题 What are the two well-known UDP ports used by RADIUS accounting servers?（）
单项选择题 What is a method by which an IP interface can be assigned to a virtual router in a PPP over ATM environment?（）