Question

Suppose an HTTP client makes a request to web server. The client has never before requested a given base object, nor has it communicated recently with the server. You can assume, however, that the client host knows the IP address of server.

Suppose also that after downloading the base file, the browser encounters a jpeg object in the base html file that is stored on gaia.cs.umass.edu, and therefore makes another GET request to server for that referenced jpeg object.

Question: How many round trip times (RTTs) are needed from when the client first makes the request to when the base page and the jpeg file are completely downloaded, assuming the time needed by the server to transmit the base file, or the jpeg file into the server's link is (each) equal to 1/2 RTT and that the time needed to transmit the HTTP GET into the client's link is zero?

You should assume that persistent HTTP 1.1 is being used. (You should take into account any TCP setup time required before an HTTP GET is actually sent by the client, the time needed for the server to transmit the requested object, and any propagation delays not accounted for in these amounts of time.)

A. 2.5 RTT
B. 5 RTT
C. 4 RTT
D. 2 RTT
E. 1 RTT

Answer 1

The number of round trip times needed from when the client first makes the request to when the base page and the jpeg file are completely downloaded is 2.5 RTTs.option a.

Step-by-step explanation:

The number of round trip times (RTTs) needed from when the client first makes the request to when the base page and the jpeg file are completely downloaded can be determined by analyzing the process. Let's break it down step by step:

1. When the client makes the initial request to the server for the base HTML file, it will take 1 RTT for the request to reach the server and for the server to transmit the base file back to the client.
2. Once the client receives the base file, it encounters a jpeg object that is stored on gaia.cs.umass.edu. Since the client has never requested this object before, it needs to make another GET request to the server for the jpeg file. This additional GET request will take another 1 RTT.
3. After the GET request for the jpeg file, the server will transmit the jpeg file to the client. Since the time needed for the server to transmit the requested object is equal to 1/2 RTT, it will take 0.5 RTT for the server to transmit the jpeg file back to the client.

Therefore, the total number of round trip times required is 1 RTT (for the base file) + 1 RTT (for the GET request) + 0.5 RTT (for the jpeg file transmission) = 2.5 RTTs.