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CS 456Computer Networks

Units
0.50
Faculty
Mathematics
Subject
Computer Science

When it runs

  1. F24
  2. W25
  3. S25
  4. F25
  5. W26
  6. S26
  7. F26
  8. W27
  9. S27

Ran in 7 of the last 7 terms. Winter 2027: scheduled, 3 lecture sections. Spring 2027: schedule not out yet.

An introduction to network architectures and protocols, placing emphasis on protocols used in the Internet. Specific topics include application layer protocols, network programming, transport protocols, routing, multicast, data link layer issues, multimedia networking, network security, and network management.

Prerequisites

Antirequisites

  • Not completed nor concurrently enrolled in any of the following:
    • CS436 - Networks and Distributed Computer Systems (0.50)
    • ECE358 - Computer Networks (0.50)
    • ECE416 - Advanced Topics in Networking (0.50)

Leads to

Fall 2026 sections

Enrolment from UW Open Data, which can trail Quest by up to two days. Instructors and rooms: Schedule of Classes.
SectionClassEnrolledMeets
LEC 001608574 / 75MW 16:00–17:20
TST 101668974 / 75Nov 3 19:00–20:50

Winter 2027 sections

Enrolment from UW Open Data, which can trail Quest by up to two days. Instructors and rooms: Schedule of Classes.
SectionClassEnrolledMeets
LEC 00156160 / 70MW 14:30–15:50
LEC 00258930 / 70MW 10:00–11:20
LEC 7012199103 / 9999Online or by arrangement
TST 10161150 / 140Mar 5 18:30–20:00

Resources

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Reviewed on UW Flow

68% liked it73% easy82% useful

From 152 ratings and 44 comments on UW Flow. The most helpful comments, quoted as written, without names. Read them all on UW Flow.

  • I put together a sick cheat sheet, that I updated after the exam to include anything that was missed, with the help of friends. Hope it helps: https://plett.dev/notes/cs456-cheat-sheet.pdf
    Very difficult course; midterm average was 50 flat, and they made the final just as hard. No curve was intended (prof Uzma Maroof) until students lobbied. It's a hell of a lot of memorization, and you don't know what kind of questions you're getting into. Good luck!

    May 2025 · didn’t like it · 2 found this helpfulOn UW FlowRemove this

  • I took this course expecting it to be easy. I wouldn't call it hard, but it is a 4th year course and should not be underestimated. Don't put off the assignments until the last minute, they are more complicated than they seem when you first read them.
    The course covers a lot more material than the assignments cover. Assignments are basically all socket programming, while the course material covers all aspects of networking (which would be difficult to make programming assignments for).

    Sep 2017 · liked it · 2 found this helpfulOn UW FlowRemove this

  • Sort of like flossing in that it's boring and tedious but ultimately you know it's good for you. Each lecture is like watching beige paint dry and bores you to death, but i guess i know how the internet works now.
    Took it with Mina, she's an ok lecturer but can be a bit aggressive on Piazza from time to time.

    Dec 2024 · didn’t like it · 1 found this helpfulOn UW FlowRemove this

  • I'm very glad I took this course and learned the concepts. Most of them are very useful to know. It was stressful for sure since I'm always scared of not memorizing and understanding enough for the exams. Luckily the marking of exams were pretty loose and the final didn't count that much (only 35%).

    Aug 2016 · liked it · 1 found this helpfulOn UW FlowRemove this

  • Content covers a good deal of what you might see in daily life, and is actually pretty interesting. Pray you get a good prof. Offering was very disorganized; lectures were not worth going to and textbook self-study was necessary. Assignments took forever to get back and midterm wasn't returned to us (but was relatively easy if you did practice problems). Final came out of left field, so do well on the midterm.

    Sep 2026 · didn’t like itOn UW FlowRemove this

Discussed on r/uwaterloo

418 posts and comments in 324 threads mention CS 456, February 2012 to December 2024. Quoted word for word, newest first; each reply sits under the post and the comment that started its branch. Search r/uwaterloo for newer posts.

Fall 2024

Upper year CS courses (or electives) that release assignments in advance 5 points, 5 comments

“Hi, I am looking to take a few courses over a summer co-op, however it begins in June. To ease my workload, I want to take courses where it is possible to work ahead on them during May before my job …”

u/OrganizationNaive452: “I've never heard of a course releasing their assignments before the first day of school if that's what you're trying to say... …”

u/OrganizationNaive452: “oh my bad! I believe CS444 is released all at once. Courses like CS451 can have assignments finished before they're released b/c testcases and assignments are same as the previous term. Not sure what's offered in spring, but maybe cs456 is similar.”

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How was it? CS459 Privacy, Cryptography,Network and Data Security 12 points, 16 comments

“I was planning on taking CS458 Computer Security and Privacy, sadly no longer offered. How was CS459 Privacy, Cryptography,Network and Data Security? For anyone taking it this term. …”

u/LaApplePear: “Thansk Ok-Conclusion & blake-potato for sharing the valuable information!! I composed a side-by-side comparison of the two mentioned courses. CS453 and CS459. …”

u/Kassaking777: “I believe for CS459, there's a coreq CS456/454. You have to either already taken one of 456 or 454, or taking one of them with 459.”

u/blake_potato: “Just wanted to update on the CS459 experience now that we’re nearing the end of the term. The course has an enrolment cap of 70 people, and although I’m not sure how many people were in the course at …”

u/blake_potato: “… They complement each other well, and I also took CS456 this term which played well with the other two. …”

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Spring 2024

CS 459 Co-requisites 3 points, 1 comment

u/Gauss_given_order: “How important/relevant are the co-reqs (CS 454/456) to the content in CS 459? When the course was offered as one of the 489s, there were no co-reqs, which makes me wonder why this change was made. Adjacently, why are these co-reqs to CS 489: Secure Programming? …”

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Winter 2024

Cs 4A Course Load 8 points, 5 comments

u/snorawr: “… Cs349 user interfaces Cs449 human-computer interaction Cs456 computer networks Cs489 advanced topics: privacy, crypto, data security Stat231 I’m tryna knock out some credits before going on exchange so they err on the easier side but still wanted interesting courses.”

u/_KareemCheese_: “… It’s really easy to do well in it - there is no coding, and all deliverables are marked very leniently (ie, you can get an 80+ with minimal effort) CS456: this was a relatively challenging class, especially compared to the two ones I mentioned before. …”

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Check it elsewhere for Fall 2026

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