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 a DNS lookup is necessary to obtain the IP address. Suppose that four DNS servers are visited before your host receives the IP address from DNS. The first DNS server visited is the local DNS cache, with an RTT delay of RTT,- msecs. The second, third and fourth DNS servers contacted have RTTs of 13, 39, and 44 msecs, respectively. Initially, let's suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Suppose the RTT between the local host and the Web server containing the object is RTTTT 97 msecs. Important: don't forget to account for the TCP overhead when using HTTP! 1) Assuming zero transmission time for the HTML object, how much time elapses from when the client clicks on the link until the client receives the object? 2) Now suppose the HTML object references 10 very small objects on the same web server Neglecting transmission times, how much time elapses from when the client clicks on the link until the base object and al 10 additional objects are received from web server at the client, assuming non-persistent HTTP and no parallel TCP connections? 3) Repeat 2. above but assume that the client is configured to support a maximum of 5 parallel TCP connections, with non-persistent HTTP Repeat 2. above but assume that the client is configured to support a maximum of 5 parallel TCP connections, with persistent HTTP 4) 5) What do you notice about the overall delays (taking into account both DNS and HTTP delays) that you computed in cases 2., 3. and 4. above? 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 a DNS lookup is necessary to obtain the IP address. Suppose that four DNS servers are visited before your host receives the IP address from DNS. The first DNS server visited is the local DNS cache, with an RTT delay of RTT,- msecs. The second, third and fourth DNS servers contacted have RTTs of 13, 39, and 44 msecs, respectively. Initially, let's suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Suppose the RTT between the local host and the Web server containing the object is RTTTT 97 msecs. Important: don't forget to account for the TCP overhead when using HTTP! 1) Assuming zero transmission time for the HTML object, how much time elapses from when the client clicks on the link until the client receives the object? 2) Now suppose the HTML object references 10 very small objects on the same web server Neglecting transmission times, how much time elapses from when the client clicks on the link until the base object and al 10 additional objects are received from web server at the client, assuming non-persistent HTTP and no parallel TCP connections? 3) Repeat 2. above but assume that the client is configured to support a maximum of 5 parallel TCP connections, with non-persistent HTTP Repeat 2. above but assume that the client is configured to support a maximum of 5 parallel TCP connections, with persistent HTTP 4) 5) What do you notice about the overall delays (taking into account both DNS and HTTP delays) that you computed in cases 2., 3. and 4. above
