Solution Set for Exam 2 CPSC 155b Spring 2003 Please note that some of the following solutions contain more information than you needed to provide to receive full credit Others only provide examples rather than an exhaustive list of correct answers 1 a i Internet ii Telephone network iii Both b False c Browsers Application layer Packet routing IP Reliable byte streams TCP Nonreliable byte streams UDP d iii e ii 2 a Advertiser supported basic services for individual users Tools customized portals and services for corporate customers Fees for extra or premium services and features for individual users e g extra storage for Yahoo Mail customers b i c iv d True e The number of points that you get for your answer will depend on how well you justify your opinion The standard explanation of why portals are something fundamentally new is that the combination of personalization and access to a very broad range of services from news to email to shopping to entertainment really isn t available from any single business in the offline world The standard answer to what is the offline analog of a portal is a shopping mall It s a flawed analogy because shopping malls aren t personalizable and portals are used for more than shopping but there are some basic similarities 3 a Peer production is production by users who are peers i e no one is above another in a formal organizational hierarchy and who self identify and selforganize by communicating directly with each other Benkler distinguishes it from two other well studied ways in which production occurs namely markets in which communication is facilitated by prices and hierarchies in which communication flows along a chain of command He claims that peer production is superior to other production modes for Internet scale information products because there are increasing returns to scale of the set of agents permitted to work with a set of resources in pursuit of projects and to the set of resources agents are allowed to work with The unbounded sets of both human capital and information inputs that can be used in peer production capture these economies of scale more effectively than can firms and to a lesser extent markets both of which rely on securing access to bounded sets of agents and information inputs to reduce uncertainty about the success of projects b i c Examples from Benkler s lecture notes include academic research the web content e g Mars clickworkers Accreditation e g slashdot Distribution e g P2P networks Other valid examples will also be given full credit d Copyleft is a condition often included in an open source license that requires the licensee to give users all of the same rights the licensee has when redistributing copies For example the licensee must allow those to whom he redistributes copies to have access to the source code e True For example IBM makes use of Linux in some of its products and services and it also sells a large number of traditional software products under traditional licenses f iv 4 a The abundance problem occurs when search engine users submit broadtopic queries e g cars computers or Afghanistan the crux of it is that the number of web pages that could reasonably be considered relevant is far too large for a human user to digest Its opposite is the scarcity problem This occurs when a user submits a very specific query e g Netscape support for the JDK 1 1 code signing API there are very few relevant web pages and it is difficult for search engines to find them The scarcity problem is not part of the exam question and no definition of it is needed for full credit The definition is included here just for your information b False c iii d Web form Index Server Doc Server Page Rank e i f True 5 a False b The TCB trusted computing base is the part of the computing environment that has to be trustworthy if there is a successful attack on the TCB then no guarantees about the correctness or security of the rest of the computing environment can be made An attestable TCB is one that can prove e g by supplying digitally signed statements to a remote machine that it is running on the local machine and that the required properties of the local computing environment hold c Correct answers include Board seat s Sale acquisition or merger approval Budget approval Approval of changes to strategy or business plan Approval of executive removal or appointment Right of first refusal on sale of shares Tag along rights follow founder sale on a pro rata basis Drag along rights force sale of company Liquidation preference Non compete conditions on founders Right to participate in subsequent rounds Anti dilution protection d Foundation documents are the government issued basic identity documents including birth certificates passports and social security cards that are relied upon to bootstrap identity and authentication systems in diverse contexts They are problematic because they are issued by many government agencies e g all 50 states and no clear consistent and effective set of definitions rules and information security practices governs their issuance and maintenance For example drivers licenses and passports may depend on each other for reissuance and replacement Lack of well understood secure handling of foundation documents creates risk of fraud and identity theft e XrML 6 a iv b iii c layering d advertising Note that there was a typo in this question The word sources was supposed to be source You will get full credit as long as your answer includes advertising e DRM technology has been developed because distributors of copyrighted works want to maintain control over their digital content after it has been distributed to untrusted users In web services we have an analogous situation Users would like to maintain control over their personal data after it has been transferred to untrusted servers 7 a An open mail relay is an SMTP server that sends mail when the sender or the machine that makes the request to send mail and the recipient are both outside the domain of the SMTP server For example if a mail server at Yale accepted a request from a machine at Harvard to send mail to a recipient at Princeton Yale s mail server would be an open mail relay b A CAPTCHA is an automated test to tell humans and computers apart i e to distinguish whether the test taker is a computer acting alone or an actual person CAPTCHAs often require the test taker to perform some task that humans can do easily but computers find difficult such as image