单项选择题 A user is connected on a DSL line and is using a PPP over Ethernet service.Which network device strips the ATM header from the datagram and investigates the PPP header?（）

单项选择题 In a DSL network，which device terminates the PPP over Ethernet subscriber’s two-wire phone line？（）

单项选择题 Which process occurs first during the Ethernet Discovery Stage process for a PPPoE service offering?（）