EBK COMPUTER NETWORKING
7th Edition
ISBN: 8220102955479
Author: Ross
Publisher: PEARSON
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Expert Solution & Answer
Chapter 2, Problem P11P
Explanation of Solution
Sharing Link:
Suppose that the link is shared by the Bob with four other users and Bob uses parallel instances of non-persistent HTTP, and the other four user’s use non-persistent HTTP with- out parallel downloads.
Parallel Connections impact:
“Yes”, the Bob’s parallel connection helps him get WebPages more quickly.
Reason:
This is because:
- Bob shared total band with four other users.
- As Bob has more connections, he can get a larger share of link bandwidth...
Expert Solution & Answer
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Please solve it correctly and give proper explanation.
Question:
Given, you want to visit “welcomebacktophysicalexams.com”. Your network has alocal DNS server and is using a recursive lookup to fetch IP addresses and RTT of 29 ms.Others in your network have already visited the above website a few hours before yourvisit.After fetching the IP address, your PC sends a non-persistent HTTP request of size 109bytes to bring 13 objects of size 31 bytes each. In this particular connection, it requiresthe PC 67ms to send the TCP request to the server.
I. What is the total RTT in ms in the DNS lookup?II. What is the total RTT in ms required (including DNS) to bring the full object toyour PC?III. What is the total file transmission time in ms after fetching the IP address?
Suppose that the average object size is 850,000 bits and that the average request rate from the institution’s browsers to the origin servers is 16 requests per second. Also suppose that the amount of time it takes from when the router on the Internet side of the access link forwards an HTTP request until it receives the response is three seconds on average (see Section 2.2.5). Model the total average response time as the sum of the average access delay (that is, the delay from Internet router to institution router) and the average Internet delay. For the average access delay, use Δ/(1 – Δ ), where Δ is the average time required to send an object over the access link and is the arrival rate of objects to the access link.
a. Find the total average response time.b. Now suppose a cache installed in the institutional LAN, Suppose the miss rate is 0.4. Find the total response time.
- Consider another carelessly written Web application, which uses a servlet
that checks if there was an active session, but does not check if the user is
authorized to access that page, instead depending on the fact that a link
to the page is shown only to authorized users. What is the risk with this
scheme? (There was a real instance where applicants to a college admissions
site could, after logging into the Web site, exploit this loophole and view
information they were not authorized to see; the unauthorized access was
however detected, and those who accessed the information were punished
by being denied admission.)
Chapter 2 Solutions
EBK COMPUTER NETWORKING
Ch. 2 - List five nonproprietary Internet applications and...Ch. 2 - Prob. R2RQCh. 2 - Prob. R3RQCh. 2 - Prob. R4RQCh. 2 - Prob. R5RQCh. 2 - Prob. R6RQCh. 2 - Prob. R7RQCh. 2 - Prob. R8RQCh. 2 - Prob. R9RQCh. 2 - Prob. R10RQ
Ch. 2 - Why do HTTP, SMTP, and POP3 run on top of TCP...Ch. 2 - Prob. R12RQCh. 2 - Prob. R13RQCh. 2 - Prob. R14RQCh. 2 - Prob. R15RQCh. 2 - Prob. R16RQCh. 2 - Prob. R17RQCh. 2 - From a users perspective, what is the difference...Ch. 2 - Prob. R19RQCh. 2 - Prob. R20RQCh. 2 - Prob. R21RQCh. 2 - Prob. R22RQCh. 2 - Prob. R23RQCh. 2 - Prob. R24RQCh. 2 - Prob. R25RQCh. 2 - In Section 2.7, the UDP server described needed...Ch. 2 - Prob. R27RQCh. 2 - Prob. P1PCh. 2 - Prob. P2PCh. 2 - Prob. P3PCh. 2 - Prob. P4PCh. 2 - Prob. P5PCh. 2 - Prob. P6PCh. 2 - Prob. P7PCh. 2 - Prob. P8PCh. 2 - Prob. P9PCh. 2 - Prob. P10PCh. 2 - Prob. P11PCh. 2 - Prob. P13PCh. 2 - Prob. P14PCh. 2 - Prob. P15PCh. 2 - Prob. P16PCh. 2 - Prob. P17PCh. 2 - Suppose you can access the caches in the local DNS...Ch. 2 - Prob. P21PCh. 2 - Prob. P22PCh. 2 - Prob. P23PCh. 2 - Prob. P25PCh. 2 - Prob. P26PCh. 2 - Prob. P27PCh. 2 - Prob. P28PCh. 2 - Prob. P29PCh. 2 - Prob. P30PCh. 2 - Prob. P31PCh. 2 - Prob. P32P
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