3. Suppose within your web browser you click on a link to obtain a Web page. The

Question

3. Suppose within your web browser you click on a link to obtain a Web page. The Web page associated with the link is an HTML file of very small size, but containing references to eight other objects on the same server. Each of these eight objects is also of very small size. Let RTT denote the round-trip time between the local host and the server containing the objects. Neglecting transmission times, how much time elapses for each of the following cases? Explain your answers. (a) Non-persistent HTTP with no parallel TCP connections. (b) Non-persistent HTTP with the browser configured for 5 parallel connections. (c) Persistent HTTP with no pipelining and no parallel TCP connections. (d) Persistent HTTP with pipelining and no parallel TCP connections.

Explanation / Answer

To visit an link/URL, the IP address associated with the URL is necessary. If the IP address for the associated URL is not cached in local host, a DNS lookup is necessary to obtain the IP address.Suppose that n (1 to n) DNS servers are visited before the host recieves the IP address from DNS.

The total amount of time to get the IP address is RTT1 + RTT2 + ….+ RTTn

Once the IP address is known, RTTo elapses to set up the TCP connection and another RTT0 elapses to request and receive the small object.

The total response time is 2RTT0 + RTT1 + RTT2 + …. + RTTn

a)Non-persistent HTTP with no parallel TCP connections.

RTT1+…+RTTn+2RTTo+ 8*2RTTo = 18 RTTo + RTT1 + …. + RTTn

b)Non-persistent HTTP with the browser configured for 5 parallel connections.

RTT1+…+RTTn+2RTTo+ 2*2RTTo   = 6 RTTo + RTT1 + …. + RTTn

c)Persistent HTTP with no pipelining and no parallel TCP connections.

RTT1+…+RTTn+2RTTo+ 2RTTo   = 3 RTTo + RTT1 + …. + RTTn

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.