1. [单选题]TCP23是（）协议端口号；UDP69是（）端口号；TCP80是（）端口号。
A. TELNET FTP HTTP
B. FTPT FTP HTTP
C. TELNET TFTP HTTP
D. TELNET DNS HTTP
2. [单选题]OSPF骨干区的区域编号为（）
A. 0.0.0.1
B. 255
C. 0.0.0.0
D. 255.255.255.255
3. [多选题]With regard to Ethernet media access methods, which of the following are true?(Choose all that apply.)
A. A device waits for an electronic signal before transmitting.
B. A device listens and waits until the media is not busy before transmitting.
C. All devices on an Ethernet segment see data that passes on the network medium.
D. Only the sender and the receiver devices see data that passes on the network medium.
E. Ethernet networks allow you to configured devises with higher transmission priority.
