John Heidemann / Teaching / CS551 / CSci551/651 Class FAQ

This web page documents frequently asked questions and their answers for John Heidemann’s section of CSci551 and CSci651. It includes questions about class, exams and grades.

Class Details

Q10: I’m reading the papers for class, and I have a good background in networking, but I’m not sure I’m getting everything out of the papers. a) what should I get out of the papers? b) is it OK if I don’t fully understand the point of all papers on my own?*

A: Wow, a two parter. Let’s see:

a) what should I get out of the papers?

We talked about this extensively in the first class of the semester, so you may want to review that lecture. But to summarize briefly: you should understand basically what the authors did, and more importantly, you should have an idea WHY they made those choices, and what they did that was NEW. You should also think about how what they did applies and doesn’t apply today.

You can also look at what I expect for exams, which is necessarily slightly different from what I expect you to figure out, offline, with the original paper and as much time as you need.

b) is it OK if I don’t fully understand the point of all papers on my own?

Yes, of course! That’s why it’s a class! And that’s exactly why we have lectures.

Please try to get as much out of the paper as you can, on your own, before class. But then see if class discussion gives you any different or additional perspectives. And please ask questions during class if things you’re not sure come up. Or if they don’t come up, ask questions anyway, either in the beginning (“what are the key ideas in this paper?” or at the end “any additional questions?”).

If you’re still puzzled after class, the your other opportunities is to come to the TA or my office hours and ask questions there. That’s especially good if you have very detailed questions.

Now, all that said, if you find you’re not getting anything out of any paper, you should ask if you’re well prepared for the class. You may find you get a lot more out of it if you review your EE450 (undergraduate networking) materials, or if you take that class and come back to CSci551 next time. (There’s nothing wrong with waiting to take CSci551 when you’re properly prepared.)

But if it’s just some of the papers, or if it’s figuring out what’s most important and not all the details, or if it’s trying to understand the context–those are exactly what we try to talk about in class.

Q11: Why do your slides so ugly? Do you have to use that background color? (It makes them hard to read when I print them, and you’re wasting all of my color ink.)*

A: DEN tells me (and I verified) that I need to use a non-white background or their camera/webcast equipment has problems. White makes the analog video image blow out. (If this changes at DEN, please let me know.)

However, this should not (I hope) cause grief when you look at the slides. I print them on a black and white laser printer and they look reasonable (black text on a grey background), IMHO. If you have a color printer you might look into telling the printer driver or PDF renderer to convert the image to greyscale for you.

As for why else the slides are ugly, I do the best I can :-)


Q20: What are the penalties for late submissions?*

A: A 25% penalty will be assessed each day any assignment is late. Assignments are usually due at noon, so this penalty would start after noon. Yes, this penalty is harsh—I don’t want to waste your time and mine with late assignments. (My general philosophy is that this is a graduate school class, and the time for coddling should have ended in high school.) I know strange things do come up and am sympathetic, though, so see slip days below.

Q21: 25% of what?*

A: The 25% is off the base score, not the actual points you got before adjustment So for a 100 point assignment, if you scored 80 points, you would loose 25 points (25% of 100, the base score), not 20 points (25% of 80, the points you would get without penalty).

Q22: I’m really late, should I bother submitting?*

A: Please talk to me.

Q23: How do I use my slip day?*

A: Because mistakes occasionally happen, I will void one day of late penalty for one assignment for each student in the semester. If you want to use this slip day you must explicitly request it in e-mail to me and to the TA, saying “I want to use my slip day on homework 2” or “…on project B”. Once a slip day is used, you cannot change it after the fact. Slip days must be used before (or when) the assignment is due, not retroactively (not days or weeks later).

Several people have asked about the format of the midterm and the final. To forstall these questions, here’s the FAQs:

Exam Format

Q30: Do you have any sample tests available?*

A: No, we don’t make old tests available. The format of the test will be include some short answer questions (one or a few words), some medium answer questions (one or two sentences), and some long answer questions (multiple parts/multiple sentence answers). The homeworks are also a good guide for what to expect (although the exam should be easier than some homework questions).

Q31: Will the test be similar to the homework?*

A: Yes, those questions cover the subject material of the questions. The hardest exam questions will probably not be as hard as the hardest homework questions.

Q32: OK, it’s like the homework, but format are the question?*

A: I usually ask four different styles of questions. Here is each with the instructions I provide on the exam, and some examples:

Exam Content

Q40: OK, that’s the format, but what will the questions be about?*

A: The material and concepts from the papers and class. Questions will usually fall into three categories: some may ask about specific concepts mentioned in class (for example, ``what are general approaches to active queue management?’’), some may ask you to relate one paper to another (for example, ``how is FQ different from RED?’’), and some may ask you to apply concepts in class (for example, ``suppose you were designing a diff-serve to send video over the network—what features would your protocols?’’).

Q41: OK, that’s what the questions be about, but what subjects will be considered?*

A: Enough already! :-) For the midterm, everything in the syllabus up to the the lecture just before the exam, not including that lecture. (Note that if class is running behind, some material originally scheduled for two lectures before the exam may appear on the lecture just before.) In years where that’s not the case, I’ll make an explicit announcement in class.

For the final, all the material.

Q42: “Up through the lecture”–what is a lecture? Will exams cover the papers or the lectures? What about material that was in one and not the other?*

A: You are responsible for all material covered in class lectures, and all material covered in the primary papers.

You need to evaluate what is important about each. Sometimes important material is only in the lecture, or only in the papers. In general, if there is important material and we don’t talk about it in lecture, I will mention the topic explicitly in lecture (as in “TCP for multimedia, that’s an interesting idea. You should think about that at home.”).

A good guide for what is import about each paper is the “key ideas” slide that we cover for each paper. However, that is a summary and may not be comprehensive, and it certainly omits some interesting details.

Q43: So the final covers the whole class, but does it cover it equally?*

A: It covers the whole class, but there may be a slight emphasis on the second half of class.

Q44: Will the supplementary material be covered on the exam?*

A: The detailed material in the supplementary papers will not be on the exam. It’s supplementary–you do not have to read it. However, it does reinforce the concepts explored in class and the primary papers. So you may find it helpful, and those concepts (explored in class and the primary papers) are certainly fair game for the exam. And of course, any concepts about networking are fair game for the exam if they relate to course content.

Q45: Are all papers equally important?*

A: Of course different papers have different things to say. Some don’t have much to say, some do. You need to judge the importance of the papers. (In class I try to touch on the most important parts of papers, but I do expect you to have read the paper yourself as well—often times we don’t cover all interesting aspects of a paper in class.)

Exam Specifics

Q50: Do we have to be able to match the authors’ names with their concepts (e.g. Ramakrishnan and Jain to DECbit) or just understand their concepts?

A: The concepts are far more important. In general, I try (but do not promise) to refer to concepts in multiple ways, like Ramakrishnan and Jain’s DECbit system. (Memorizing what [Ramakrishnan90a] is is not very helpful in the long run.) **

Q51: What about the formulas? Do I have to memorize all the formulas in the papers? Sometimes they’re really long or really hard, and I don’t like math.

A: I will not expect you to derive formulas from scratch on the exam, nor will I expect you to memorize complicated formulas. The concepts behind some simple formulas are so fundamental you should know them, though (for example: what is bandwidth-delay product). You should also be familiar enough with the formulas that, given the formula and some context it, you can draw some conclusions about what it says. And you should certainly know the implications of the work (including the formulas).

Q52: Will the exams be open-book?*

A: No.

Q53: Why are you so cruel? I can’t memorize all that material.*

A: I have a couple of reasons behind why the exam is closed book. First, an open-book exam is usually a different style than the kind of exam I prefer–it often focuses more on specific details rather than the bigger picture. I don’t want to write (or grade or reward) that style of exam. Second, in the real world, it is important to be able to react to questions on-the-fly, to justify the choices you’ve made and react to proposals others make. This skill requires that you have some background in your head and not just in books on a shelf. A closed-book exam partly tests for that skill.

Q54: Ok, closed book. But surely I can have one page of notes, can’t I?*

A: No. For my reasoning, see above. However, you may find that preparing such a one-page summary is excellent preparation. But do not bring it to the exam.

Exam Strategies

Q60: I ran out of time on the midterm. What should I do?*

A: Often students run out of time because they write answers that are too long. Almost always, each part of a question can be answered with a single sentence, sometimes even with just a word or part of a sentence. Only occasionally are multi-sentence answers required. One way to get much more out of the time you have in the exam is to write shorter answers.

In an exam with many different topics where you may run out of time, it’s often prudent to skip harder questions (or ones that are hard to you) and come back to them later. (Just don’t forget.)

Grade Questions

Q70: I’m not happy with my grades in class so far, what should I do?*

A: I often get this question after midterms come out. My answer is usually the same. Usually scores reflect how much work you’re putting into class. Some questions to help you try and improve what you’re getting out of class:

Q71: Do you curve the grades?*

A: Because I do not know exactly how hard exams and projects are, I do not assign grades on a pre-determined scale.

Copyright © 2002-2018 by John Heidemann