FTP是基于_(1)_實(shí)現(xiàn)的文件傳輸協(xié)議，使用此協(xié)議進(jìn)行文件傳輸時(shí)，F(xiàn)TP客戶(hù)和服務(wù)器之間建立的連接是_(2)_，用于傳輸文件的是_(3)_連接。TFTP是基于UDP實(shí)現(xiàn)的簡(jiǎn)單文件傳輸協(xié)議，它共有五種協(xié)議數(shù)據(jù)單元PDU，其中數(shù)據(jù)PDU一次可以攜帶的數(shù)據(jù)最多是_(4)_，當(dāng)傳輸?shù)奈募�長(zhǎng)度恰好是其整數(shù)倍時(shí)，則文件傳輸完畢后，還必須在最后發(fā)送一個(gè)_(5)_。

　　⑴A.IP B.TCP C.UDP D.ICMP

　�、艫.數(shù)據(jù)連接 B.控制連接和指令連接

　　C.控制連接和數(shù)據(jù)連接 D.數(shù)據(jù)連接和指令連接

　�、茿.數(shù)據(jù) B.指令 C.控制 D.UDP

　　⑷A.384 B.512 C.1024 D.1500

　�、葾.確認(rèn)PDU B.應(yīng)答PDU C.請(qǐng)求PDU D.無(wú)數(shù)據(jù)的數(shù)據(jù)PDU

　　答案：BCABD

　　Flow control is a function that prevents network congestion by ensuring that _(1)_ do not overwhelm_(2)_ with data.

　　There are three commonly used methods for handling network congestion . _(3)_is used by network devices to temporarily store bursts of excess data in memory until they can be processed. _(4)_ are used by receiving devices to help prevent their buffers from overflowing . _(5)_ is a flow-control scheme in which the source device requires an acknowledgment from the destination after a certain number of packets have been transmitted.

　　⑴⑵A.transmitting devices B.transmitted devices

　　C.receiving devices D.received devices

　�、洽娶葾.Buffer B.Source-quench messages

　　C.window D.Windowing E.Buffering Answer：ACEBD