(25)

(25)

(24)

(23)

(22)

In　the　following　essay,　each　blank　has　four　choices.　Choose　the　best　answer　and　write　down　on　the　answer　sheet.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　preventing(73)is(74)control.　When　a　host　wants　a　new　virtual(75),　it　must　describe　the　traffic　to　be　offered　and　the　service　expected.

(19)

(20)

(18)

(17)

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

 (66) is a one-way function that takes an arbitrarily long piece of plaintext and from it computes a fixed-length bit string.

 (67) is a protocol that most USENET machines now use it to allow news articles to propagate from one machine to another over a reliable connection.

 (68) is an approach preferred by cable TV providers. In this solution the fiber terminates at an optoelectrical converter and the final segment is a shared coaxial cable.

 (69) is a device used to connect two separate network that use different communication protocol.

 (70) is a digital-to-digital polar encoding method in which the signal level is always either positive or negative.