题目内容：
根据下列题干，回答题：For each blank, choose the best answer from the four choices and write down on the answer sheet.
（ 1 ）is a protocol that a host uses to inform a router when it joins Or leaves an Internet multicast group.
（ 2 ） is an error detection code that most data communication networks use.
（ 3 ）is an interior gateway protocol that uses a distance vector algorithm to propagate routing infor- mation.
（ 4 ）is a transfer mode in which all types of information are organized into fixed form cells on an a- synchronous or non - periodic basis over a range of media.
（ 5 ） is an identifier of a web page.
请选择（ 1 ）处最佳答案
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答案解析：