DES加密算法采用的密码技术是(61)，它采用(62)bit密钥对传输的数据进行加密，著名的网络安全系统Kerberos采用的是(63)加密技术。公钥密码是(64)，常用的公钥加密算法有(65)，它可以实现加密和数字签名。

(70)

(71)

(69)

(68)

In low-speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high-speed networks, this approach often works poorly, because in the(71)between sending the notification and notification arriving at the source, thousands of additional(72)may arrive. In ATM network , a major tool for pre- venting(73)is(74)control. When a host wants a new virtual(75), it must describe the traffic to be offered and the service expected.

(66)

(64)

(65)

(63)

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

  (66) 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.

  (67) is a professional organization of individuals in multiple professions which focuses on effort on lower-layer protocols.

  (68) functions with two layers of protocols. It Can connect networks of different speeds and can be adapted to an environment as it expands.

  (69) is the popular LAN developed under the direction of the IEEE 802.5.

  (70) is the popular backbone technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.