Compsci 82, Fall 2009, DNS Questions 9/24/09
By entering your name/net-id below you indicate you are in class on
September 2 to answer these questions and that you have answered them.
Name: ___________________ Net id: _______ ||| Name: ___________________ Net id: _______
Name: ___________________ Net id: _______ ||| Name: ___________________ Net id: _______
In a 2008 case, a federal US District judge ordered
wikileaks.org to be "shutdown" by
having its domain name registrar disable the domain name. Wikileaks
is a whistleblowing site that claims "We are of assistance to
peoples of all countries who wish to reveal unethical behavior in
their governments and institutions. We aim for maximum political
impact.
In a
Feb 20, 2008 NY Times article reporting on the disabling
of the domain name this report is given:
The order had the effect of locking the front door to the Wikileaks.org
site --- a largely ineffectual action that kept back doors to the site,
and several copies of it, available to sophisticated Web users who knew
where to look.
- Explain in a few words why people were still able
to access Wikileaks at http://88.80.13.160/ despite the removal
of www.wikileaks.org from the domain name system.
- Explain in a few words why
the mirror site http://wikileaks.de was still
available
even though wikileaks.org was not.
-
Using the
network
solutions web-based WhoIs service indicates that
the IP address 211.151.227.142 corresponds
to the Asia Pacific Network Information Centre
with a CIDR of 210.0.0.0/7 and
a range of addresses from 210.0.0.0 -- 211.255.255.255. How many
addresses is this expressed as a power of 2? Explain how you
arrived at your answer.
-
Using just-ping.com to ping
the address www.duke.edu from several locations throughout the
world shows that some packets are lost in traveling to Duke's webserver
from different computers in the world. Is
this most likely because of DNS issues or because of routing and
Internet traffic issues. Justify your answer briefly.
- The ping program relies on ICMP: Internet Control Message Protocol
to do its work. What organization do you think developed this protocol?
- If IANA were to allocate every possible IPv4 address at the rate
of one billion addresses per second, how long would it take to run out
of addresses? Justify your answer. (approximate is ok)
- If IANA were to allocate every possible IPv6 address at the rate of
one billion addresses per second, how long would it take to run
out of addresses. Justify your answer. (approximate is ok)
- BGP routers may exchange routing tables --- a full table contains
about 300,000 entries. Why is this number so much smaller than the
number of IP addresses in use in the world which is over four billion?
- What do the numbers in the cartoon below have in common?
