P7. Suppose within your Web browser you click on a link to obtain a Web page.The IP address for the associated URL is not cached in your local host, so aDNS lookup is necessary to obtain the IP address. Suppose that n DNSservers are visited before your host receives the IP address from DNS; thesuccessive visits incur an RTT of RTT1, . . ., RTTn. Further suppose that theWeb page associated with the link contains exactly one object, consisting of asmall amount of HTML text. Let RTT0 denote the RTT between the local hostand the server containing the object. Assuming zero transmission time of theobject, how much time elapses from when the client clicks on the link untilthe client receives the object? P8. Referring to Problem P7, suppose the HTML file references eight very smallobjects on the same server. Neglecting transmission times, how much timeelapses witha. Non-persistent HTTP with no parallel TCP connections?b. Non-persistent HTTP with the browser configured for 5 parallel connections?c. Persistent HTTP?
P9. Consider Figure 2.12, for which there is an institutional network connected tothe Internet. Suppose that the average object size is 850,000 bits and that theaverage request rate from the institution’s browsers to the origin servers is 16requests per second. Also suppose that the amount of time it takes from whenthe router on the Internet side of the access link forwards an HTTP requestuntil it receives the response is three seconds on average (see Section 2.2.5).Model the total average response time as the sum of the average access delay
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- Fall '14
- IP address, World Wide Web, Web server, Domain Name System, average response time, RTTs