Question

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 n DNS servers are visited before your host receives the IP address from DNS; the successive visits incur an RTT of RT T1, ..., RT Tn. Further suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Let RT T0 denote the RTT between the local host and the server containing the object. Assuming zero transmission time of the object, how much time elapses from when the client clicks on the link until the client receives the object?

Answer 1

Answer:-------------

The total amount of time to get the IP address is
RTT₁ + RTT₂ + ---------- +  RTT_n
.
Once the IP address is known,RTT₀ elapses to set up the TCP connection and another RTT_O elapses to
request and receive the small object.
The total response time is
2RTT_o + RTT₁ + RTT₂ + ------------------- + RTT_n