Compsci 82, Fall 2009, Midterm Answers

This is the midterm to which answers are given below.

  1. The Internet is a network of networks, perhaps better it's a network of Autonomous Systems (AS). Communication between the ASs depends on BGP, in general other protocols help communication in the Internet.

  2. A change to IPv6 is needed because with IPv4 we have 32-bit addresses, for a total of 232, or about 4 billion addresses. That's not enough for all the devices connected to the Internet today, even with NAT (Network Address Translation) helping. We'll run out soon. With IPv6 an address is 128-bits, for 2128 addresses. This is about as much as half the atoms in the Universe, so that will likely be enough. The government is interested in this because (a) the economy depends to a large extent on the Internet, (b) the government might lead by examples in getting companies to support IPv6 and (c) the Internet is a common good, so the government should arguably do the right thing in ensuring it continues to work well.

  3. Open source, particularly GPL'd open source, could not sustain or support a monopoly. An open-source license requires that the source code be available for free or minimal cost for others to use. With a GPL license, anyone changing the code must also make the code licensed the same way, the so called "viral" nature of the GPL. Since a monopoly requires stifling competition, it's not possible for code that's given away to be unavailable to competitors, so it would be difficult for a company to build a monopoly on open source.

  4. The IETF develops open standards. Membership in the IETF is open to anyone. The standards and people work on a consensus driven model, in fact "rough consensus and running code" is a label applied to the workings of the IETF. Since standards are developed by members whose company/other affiliation isn't required, and anyone can participate, the standards are open. The standards are also released on the Internet for public perusal and comment, both during the development process and afterwards. The IETF isn't hierarchical, no one person is in charge, it's the epitome of open-ness in some respects.

  5. The site is arguably legal. It uses DMCA like protection to allow copyright-holders to take down material. If students put up their own interpretation of a professor's lecture, that's protected by copyright since copyright is about the expression of ideas, not the ideas themselves which are not copyrightable. Just as with Cliffs/Spark notes, if student notes aren't copying verbatim from the professor, they're legal. This seems similar to student-study groups, which universities likely support, but now it's online and available to the public.

    The ethics are open to individual interpretation, but most answers to this question argued that this is an ethical endeavor. It's non-profit, clearly trying to benefit students and others, not making money, attentive to demands from the professoriate even when those demands may be too strong, e.g., "take down that blog".