Question 2: Answer following question with proper explanation.

1. List 3 fields in the HTTP header indicating the current timestamp, original timestamp and size of the content.

2. Is it possible to use only http for email communication? Explain.

3. 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 5 DNS servers are visited before your host receives the IP address from DNS; the successive visits incur an RTT of RTT1 , ..., RTT5 . Further suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Let RTT0 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? (Assume RTT0 = 2.3ms and RTTi = 1.7ms where i = 1...5)

Question 3: Refer to Question#2C and suppose the HTML file have reference to 15 small images on the same server. Neglecting transmission time, how much time elapses with

1. Non-persistent HTTP with no parallel TCP connections?

2. Non-persistent HTTP with the browser configured for 5 parallel connections?

3. Persistent HTTP?