Problem 1. Web and HTTP Quickies. a) True or false? A user requests a Web page that consists of some text and three images. For this page, the client will send one request message and receive four response messages. Give one or two sentences of explanation. b) True or false? The Date: header in the HTTP response message indicates when the object in the response was last modified. Give one or two sentences of explanation. c) Why do you think the HTTP protocols run on top of TCP rather than on UDP? d) What is an important difference between a web cache, and a browser cache? Your answer need only be a couple of sentences long. There are a number of correct answers here.
Question
Problem 1. Web and HTTP Quickies.
a) True or false? A user requests a Web page that consists of some text and three images. For this page, the client will send one request message and receive four response messages. Give one or two sentences of explanation.
b) True or false? The Date: header in the HTTP response message indicates when the object in the response was last modified. Give one or two sentences of explanation.
c) Why do you think the HTTP protocols run on top of TCP rather than on UDP?
d) What is an important difference between a web cache, and a browser cache? Your answer need only be a couple of sentences long. There are a number of correct answers here.
Solution
a) True. For each component of the web page (the text and each of the three images), the client sends a request and receives a response. Therefore, in total, the client will send one request for the text and one for each image, and receive a corresponding response for each, making four response messages in total.
b) False. The Date: header in the HTTP response message indicates the time at which the server believes the message was sent, not when the object in the response was last modified. The Last-Modified: header indicates when the object was last modified.
c) HTTP protocols run on top of TCP rather than on UDP because TCP provides reliability. TCP ensures that all packets arrive and that they do so in the correct order. This is crucial for transmitting web pages as losing packets or receiving them out of order could result in a web page not displaying correctly.
d) A web cache is a mechanism for the temporary storage (caching) of web documents, such as HTML pages and images, to reduce bandwidth usage, server load, and perceived lag. A browser cache, on the other hand, is a cache implemented by the web browser to store web pages on the local computer. This allows the browser to load previously visited pages more quickly because it can read the page's data from the local disk instead of downloading it from the web again.
Similar Questions
b) True or false? The Date: header in the HTTP response message indicates when the object in the response was last modified. Give one or two sentences of explanation.
Answer the following:a. True or false?i. A user requests a Web page that consists of some text and three images. Forthis page, the client will send one request message and receive four responsemessages.ii. Two distinct Web pages (for example, www.mit.edu/research.html andwww.mit.edu/students.html) can be sent over the same persistent connection.iii. With nonpersistent connections between browser and origin server, it ispossible for a single TCP segment to carry two distinct HTTP requestmessages.iv. The Date: header in the HTTP response message indicates when the object inthe response was last modified.v. HTTP response messages never have an empty message body
a) True or false? A user requests a Web page that consists of some text and three images. For this page, the client will send one request message and receive four response messages. Give one or two sentences of explanation.
What is an important difference between a web cache, and a browser cache?
A user enters a Web address in a browser, and a request for a file is sent to a Web server. Which of the following best describes how the file is sent back to the user?The file is broken into packets and sent over a network. The packets must be reassembled by the user’s computer when they are received. If any packets are missing, the browser re-requests the missing packets.The file is broken into packets and sent over a network. The user’s browser must request each packet, in order, until all packets are received.The server attempts to connect directly to the user’s computer. If the connection is successful, the entire file is sent at once. If the connection is unsuccessful, an error message is sent to the user.The server repeatedly attempts to connect directly to the user’s computer until a connection is made. Once the connection is made, the entire file is sent.
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