The Internet: Crash Course Computer Science #29


Today, we’re going to talk about how the Internet works. Specifically, how that stream of characters you punch into your browser’s address bar, like “”, return this very website. Just to clarify we’re talking in a broader sense about that massive network of networks connecting millions of computers together, not just the World Wide Web, which is a portion of the Internet, and our topic for next week. Today, we’re going to focus on how data is passed back and forth – how a domain name is registered by the Domain Name System, and of course how the data requested or sent gets to the right person in little packets following standard Internet Protocol, or IP. We’ll also discuss two different approaches to transferring this data: Transmission Control Protocol, or TCP, when we need to be certain no information is lost, and User Datagram Protocol, or UDP, for those time sensitive applications – because nobody wants an email with missing text, but they also don’t want to get lag-fragged in their favorite first person shooter.

Want to run traceroute on your computer? See directions below. Remember you can replace “” with whatever website you want!

Traceroute on Windows
1. Press the Start Button
2. Type “CMD” and press “Enter”
3. In the Command Prompt type “tracert”

Traceroute on Mac
1. Click on the “Go” drop down menu
2. Click on “Utilities”
3. Open Terminal
4. Type “traceroute”

Traceroute on Linux
1. Open Terminal by typing CTRL+Alt+T
2. Type: “traceroute”

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    what is the rush? could she speak a bit slower or more clear?

  2. Clyde says

    These videos would be great if she actually slowed down in her talking, she just goes of rambling with no break or breath in between, it's rushed and unnatural.

  3. Sibti ali says

    This video single-handedly made me understand more about networking than a whole year of my university module.

  4. Become Heroic says

    Take a breath

  5. Mo Ki says

    much better than CompTia!!

  6. daniel lipatov says

    why did school make me watch this

  7. DNAunion says

    8:19 "It's like the phone book for the Internet"Zoomers: Phone book? What is that?

  8. Christian Martin says

    “You computer may not know which application to give the data to, Skype or call of duty? “That is an insult to Reddit

  9. mike hosken says

    I’m so so sick of English people calling a router a rooter. She can pronounce traceroute correctly and route but some how they can’t pronounce router. Every time I hear it, my head explodes. Excellent series very informative but stop saying roooooooter !!!!!!

  10. Rowan Brown says

    Checksum… sounds yummy ?

  11. Bipolar Penguin Music says

    The production of this is amazing, explained so well from scratch. I am honestly impressed, thank you so much for this!

  12. 리주민 says

    Hopefully they will run analog tv waves besides digital to prevent the Skype syndrome you described, plus the CD skip and "no content this channel" blank screens. I'd prefer analog snow to no tv. Country is nice…if I have a tv ?

  13. raivolution says

    Two Professors with PhDs in computer science spent 6 hours in lectures trying to explain this in my Master's lectures. You guys did it in 12 mins, phenomenal!

  14. Hannah Walker says

    why is this making more sense then my actual networking class?

  15. YongKang Chia says

    Wow so awesome! Learning this for my internship for computer networking 🙂

  16. K - Feb says

    Awesome job explaining this ?

  17. Snowy says

    Whole digital communications course in one video. Respect.

  18. L P says


  19. Jarrod C says

    the session layer wasnt explained that well

  20. Boris The Soviet Love-Hammer says

    Might be worth noting that your home "router" is actually a switch, a router, and wireless AP combined.

  21. Chethana Gowda ChaZe says

    has my youtube auto increased playback speed?

  22. Naved Zaman says

    Why you people talk so quickly. It is hard to understand by non English person.

  23. Rappin Rhinosheep says

    9 hops!

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