单选题 For each blank, choose the best answer from the four choices and write down on the answer sheet.
(71) is a channel's capacity which directly reflects the data transfer rate of the channel.
(72) is an interior gateway protocol that uses a distance vector algorithm to propagate routing information.
(73) is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.
(74) 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.
Ethernet is the popular LAN developed under the direction of the (75) .