单项选择题
Which of the following attacks occurs when a hijacker intercepts traffic, modifies it, then sends thetraffic?（）
A.DoS B.Smurf C.Man-in-the-middle D.Phishing
单项选择题 Which of the following is the BEST network device to allow multiple network connections to beterminated in one spot?（）
单项选择题 Which of the following uses TCP?（）
单项选择题 Data encryption and decryption occurs at which layer of the OSI model?（）
