●For each blank，choose the best answer from the four choices and write down on the answer sheet．

(66) is a protocol that a host uses to inform. a router when it joins or leaves an Internet multicast group．

(67) is an error detection code that most data communication networks use．

(68) is an interior gateway protocol that uses a distance vector algorithm to propagate routing information．

(69) is a transfer mode in which all types of information are organized into fixed form. cells on an asynchronous or non-periodic basis over a range of media．

(70) is an identifier of a web page．

(66) A．SMTP

B．ICMP

C．RARP

D．IGMP

(67) A．4B／SB

B．CRC

C．Manchester Code

D．Huffman Code

(68) A．OSPF

B．RIP

C．RARP

D．BGP

(69) A．ADSL

B．ATM

C．Frame. Relay

D．DDN

(70) A．HTTP

B．URL

C．HTML

D．TAG