In the following essay，each blank has four choices．Choose the most suitable one from the four choices and write down in the answer sheet．

Open Shortest Path First(OSPF)is a (66) routing algorithm that (67) work done on the OSI IS-IS intradomain routing protocol．This routing，as compared to distance-vector routing，requires (68) processing power．The Dijkstra algorithm is used to calculate (69) OSPF routing table updates only take place when necessary， (70) at regular intervals．(66)

A．distance-vector

B．link-state

C．flow-based

D．selective flooding(67)

A．derived from

B．deviated from

C．was derived from

D．was deviated from(68)

A．more

B．less

C．same

D．most(69)

A．routes

B．road

C．distance

D．cost(70)

A．but rather

B．rather too

C．rather than

D．rather that

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[单选题]F．or 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

[单选题]Read the following text. Choose the best word(s) for each numbered blank an

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