单项选择题 A company has recently received a new ADSL backup Internet connection. Which of the followingwill MOST likely be used between the modem and the ISP?（）

单项选择题 A router that takes the workstations internal IP address and changes it to another IP address whenit sends the data outside of the network is an example of which of the following?（）

单项选择题 Which of the following protocols is commonly used for VoIP technology?（）