# Compsci 82, Fall 2009, November 16

By entering your name/net-id below you indicate you are in class on
November 16 to answer these questions and that you have answered them. As
many as four can claim credit for answers on one sheet.
Name: ___________________ Net id: _______ ||| Name: ___________________ Net id: _______
Name: ___________________ Net id: _______ ||| Name: ___________________ Net id: _______

- Suppose Moore's law holds for the speed of computing, and we
use the "doubles every two years" version of the law. If computers
execute one billion instructions a second today, how many instructions
per second will be executed in 2019? Why?

- In 1998 Jakob Nielsen said bandwidth grows by 50% a year (measured
in downloading bits-per-second). The Duke wireless network uses
802.11n, which is about 100 Mbit/s or 100 Megabits/second. This
is about 100 million bits/second. I can download a
bootleg/illegal copy
of
*Harry Potter and the Half-Blood Prince* that is roughly 1.4
Gigabytes in size. That's 1.4 billion bytes and a byte is 8 bits. How
long will it take to download via the 802.11n network. How long
will it take in 2019 if Nielsen's law holds?

- The url
`www.youtube.com?v=w2FxTQCgA9U` is valid. If every
URL with the same length is valid, and any digit as well as upper/lower
case letters can be used, how many possible URLs/videos are
there?

### Google

Google log anonymizing paper

- In the article you can find the following phrase, "
*Since each octet (the
numbers between each period of an IP) can contain values from
1-255, ...*". Explain why the numbers are between 1 and
255.

- If you remove cookies every few months will some of the
author's concerns by eliminated (e.g., on the second page when
the author talks about a "9-month-old search log ... because the cookie
values remain".