4.下图是校园网某台主机使用浏览器访问某个网站,在地址栏键入其URL时用sniffer捕获的-|||-数据包。-|||-Sniffer Portable - Local,Ethernet (Line peed-|||-Eile Monitar Capture Display Iools Database Window Help-|||-Defauk-|||-a-|||-No Status ISource Address Dest Addres Summaty [B] Rel. Time-|||-JACKSON [59.67 148.5] DNS =42011 =QOEP NANE=ftp bupt.ed cn 75-|||-148 CKSON DNS =42011 =QDEP STAT=OK =FEP bupt edu cn 91 0:00-|||-bupt edu.cn TCP D=21 S=1039 SYN = ① =0WII=65535-|||-f edu.cn TCP D=1039 S=21 SYN ACK=577568801 =2351764071 ykparallel =0 =5840 62 0:00 62 0:00-|||-JACKSON tp.bupt edu.cn TCP C PORT=1039 USER anonymous 70 0 00-|||-=1039 5=21 D=21 5=1039 ACK= ② =65535 60-|||-edu.cn 220(vsFTPd 2.0.5) 74 0:00-|||-tp bupt cn FTP FTP-|||-ftp.bupt cn CP =577568881 =5840 60 0:00-|||-edu.cn|JACKSON FTP R PORT=1039 331 Please sp ecify the password 88 0:00-|||-J edu.cn FTP C PORT=1039 PASS IEUs er@ 68 0:00-|||-ftp.bupt edu.cn ACKSON PORT=1039 230 Login suc cessful-|||-9 JACKSON ftp.bupt edu.cn FTP C PORT=1039 7 0:00-|||-20 tp,bupt edu,cn| ACKSON TP R PORT=1039 501 Optio n not unde rstood. 68 0:00-|||-21 JACKSON ftp.bupt edu.cn FTP C PORT=1039 yst 60 0:00-|||-82 0:00-|||-22 p.bupt.edu.Cn|JACKSON FTP R PORT=1039 215 UNIX TVE e L8 73 0:00-|||-P 0 last frag ment-|||-rp Fragment offse t 0 bytes-|||-IP Time to li ve 128 seconds /hops-|||-IP Protocol 6(TCP)-|||-IP Header ch ecksum=C6D B (correc t)-|||-IP Source addr ess =[202.113.78113].JACKSON-|||-IP Destinat ion addre ss= [211.68.71801. ③-|||-IP No opti ons-|||-IP-|||-ce header-|||-TCP-|||-TCP Source port 1039-|||-TCP Destination port 21(FTP-ct x1)-|||-TCP Sequence number 577568801-|||-TCP Next expe cted Seq number 577568817-|||-TCP Acknowle dgment n umber 2351764092-|||-TCP Data offs et 20 bytes-|||-0000000 00 e0 fc ae 8f 00 142a 4f 70 46 08 00 45 00-|||-00000010 00 38 00 6d 40 00 80 06 c6 db ca 71 4e 71 d3 44 8.m@.c.欺-|||-00000020 47 50 04 0f 00 15 22 6d 0021 8c 2d 12 7c 50 1-|||-00000030: ff eb 2f 21 00 00 553 0 61 6e 6 f be USER an-|||-00000040 675 0d 0a-|||-Expert Decode Matrix A Host Table P Protocol Dist Statistics-|||-For Help,press F1 square 业 square D-|||-请根据图中信息回答下列问题。(每空2分,共10分)-|||-(1)该URL是[16]。-|||-(2)该主机的IP地址是[17]。-|||-(3)图中的①②③删除了部分显示信息,其中①应该是[18 ],③应该是[19]。-|||-(4)该主机配置的DNS服务器的IP地址是[20 】。