1、Chapter1.eAlice Web-account(such asor)sendsamessagetoBob,whoChapter1.eAlice Web-account(such asor)sendsamessagetoBob,whosesfromserver using POP3. Discuss how the message gets from host Bobshost.Besuretolisttheseriesofapplication-tusedtomovethemessagenthetwo(1)Alice 的郵Alice 的報(bào)文發(fā)送Alice 郵箱的服中Alice 使用一個(gè)

2、基Web 的電子郵件賬戶，所以使用的http 協(xié)議郵箱的服務(wù)器收到報(bào)文后，將報(bào)文放到報(bào)文發(fā)送隊(duì)列中將該報(bào)文發(fā)送到Bob 郵箱的服務(wù)器中，所使用的是SMTP (3)Bob 郵箱的服務(wù)器收到報(bào)文后，將報(bào)文放到Bob 的郵箱中。Bob 要閱讀郵件時(shí)，使用 POP3 協(xié)議將郵件從服務(wù)器傳回到主機(jī)中所以，所使用的應(yīng)用層協(xié)議分別是HTTP,SMTP,POP3 2.The UDP server described in Section 2.7 only needed one whereas the TCP server described in Section 2.6 needed two Why?Ifth

3、eTCPserverweretosupportnsimultaneousconnections,from a different nt host, how many sockets would the TCP 因?yàn)?是面向連接的需要一個(gè)歡迎套接字歡迎來(lái)自運(yùn)行在任機(jī)器上的客戶因?yàn)?是面向連接的需要一個(gè)歡迎套接字歡迎來(lái)自運(yùn)行在任機(jī)器上的客戶機(jī)程序發(fā)起的連接當(dāng)客戶機(jī)通過(guò) 向服務(wù)器連時(shí)，會(huì)創(chuàng)建一個(gè)新的套接字。而 不需要這些UDP 一個(gè)套接字就可以。如果TCP 服務(wù)器提供來(lái)自于不同客戶主機(jī)個(gè)并行連接，則TCP 服務(wù)器需n+1 個(gè)套接字3.Trueora) e a user requests a t co

4、nsists of some text two images. For this page, the nt will send one request message recievethreeresponseb) Two distinct ges h.html nbrowserandoriginserver,sible for a single TCP segment to carry two distinct HTTP d) The Date: he HTTP response message indicates when heresponsewaslaste within your web

5、 browser you click on a link to obtain a page.ttheIPaddressforthee within your web browser you click on a link to obtain a page.ttheIPaddressforthetedURLisnotcachedyour local host, t a DNS look up is sary to he address.etnDNSserversarevisitedbeforeyourhostthe IPaddress from DNS; the sive visits incu

6、r a RTT of RTT1, RTTn. Further et ge ted with the link exactly one object, a small amount of HTML text. Let RTT0 denote RTT n the local host and the server containing the Aming zero time of the object, how much time fromwhenthentclicksonthelinkuntilthentreceivesthe獲取web IP 地址所需要的獲得 IP 地址后機(jī)要向包含對(duì)象的服務(wù)器

7、TCP 需要兩個(gè) RTT0，因?yàn)閷?duì)象是少量的 HTML 文本，且假定傳輸該象時(shí)0，所以從客戶機(jī)點(diǎn)擊該到它接受到該對(duì)5.Referring to question 4, e the page contains three very objects. Neglecting times,howmuchtimeelapses以下3 中情況獲取IP 地址的時(shí)間都是一樣的，為(a)nonpersistentHTTPwithnoparallelTCP非持(a)nonpersistentHTTPwithnoparallelTCP非持久連接中HTML 文件以及3 個(gè)對(duì)象中的每一個(gè)都要連接后發(fā)送請(qǐng)求，所以分別需要2 RTT0。所以總(b)n