Computer Networks: Crash Course Computer Science #28

[@Frankx520]

I literally cried when finally understand these things.

[@meddahmadjid4284]

like me ....its amazing course

[@KevenMaker]

This was incredibly well written! At first glance it is all a bunch of complicated stuff, but you guys can explain it all in a way that is so, so easy to understand. I love CrashCourse because everything just sounds so simple here, thanks for doing it : )

[@rodsmade]

im legit crying because i know from experience how hard it is to come across such diligent, comprehensive explanations out there. some people are not willing to share. some people do not care that their point come across. so seeing crash course do all this work to make things digestible and understandable is overwhelming really, and i'm just so grateful!

[@amilcrrr]

5 semesters of computer science in 12 mins. Amazing!!

[@GuhaArnab]

😂

[@harshrana3518]

Is this a joke or truth?

[@cyin974]

@@harshrana3518 It's more like a broad introduction to what you would learn in a cs course. You see the big picture and how different things link together. Computer science in universities often go more in depth (sometimes with unnecessary details) into each topic.

[@meddahmadjid4284]

exactly its that

[@nullptr.]

This channel does a truly amazing job of bringing computer science knowledge to anyone for free and with easy, intuitive explanation. Thanks guys, keep up the great work.

[@tirthikabandi2354]

I have spent a year studying this in my college but now I feel like I finally understood it. Great job!!

[@JM-us3fr]

I love Carrie Ann! I just want to give her a hug. One of the best hosts of Crash Course

[@glaxmattbas]

I would make a UDP joke but you might not get it

[@sheebeedeebee2571]

As a TCP joke, I acknowledge your UDP joke

[@javierescudero6502]

The UDP joke better not answer

[@诸葛青-b2r]

how can you know if i received but i pretend i didnot or i just not received

[@danielseraphim9962]

To ack or not to ack

[@RobertoRodriguez-gn3tt]

Lol

[@old-moose]

Grace Hopper said that in the early days of computers, the military kept wanting to build bigger computers to solve bigger problems. Her advice: "When my daddy had a stump on the farm that one ox couldn't pull out, he didn't wait to grow a bigger one. He would chain 2 of them together to pull out the stump. If it didn't move, add another ox until it did. We don't need bigger computers. We just need to get them to pull together." Imagine the size of a computer that can do everything my smart phone can do but without the Internet!

[@NarpytheCrimeDog]

Don't tell me what to imagine. I'm an adult and I'll imagine boobies instead.

[@amidst5962]

Really amazing!

[@presbytes]

About to finish up my Computer Science degree this May. I've been geeking out over these crash course videos, feels like I'm reliving those years.

[@mccataldo]

Please don't ever stop making these. Ever.

[@verified_tinker1818]

Half of my networking class packed into a well-paced, easily-digestable 12-minute video. Love you, CrashCourse.

[@TheDeeMat]

As a Cisco Certified Networking Professional (CCNP)....this is probably my favorite part of this series :-D

[@mark1h2023]

David Matthews I took a class in Cisco. I completely agree with you.

[@DuluthTW]

Awesome. You clarified some things I've always been a little fuzzy about and clearly explained some things I thought I understood but obviously didn't quite. Thanks!

[@ashishjha9262]

Give her a Nobel Prize or Turing award. She is the Coolest professor of Computer Science. Hats off!!!

[@marksusskind1260]

I've been using computers since middle school in 1978. I recognize a lot of the material in this course. I loved working on computers in school, but I couldn't carry that excitement outside except for that brief time I fiddled around with a tower computer at home. I was excited for Windows 95, 98, and ME. By the time XP came around, I waited for my office to upgrade first. I only started using a cellular phone in 2001. I haven't moved to smartphones or tablets. I took some MOOC coding courses, but, once the course was over, I didn't do anything more except for falling into some coding rabbit hole. Wolfram-Alpha already does what my code was going to do. I suppose it's too bad I can't go to high school for the rest of my life.

[@lilhani9519]

I paused the video so she can breath lol

[@theinquisitor18]

I'm a computer science major. Love these.

[@theinquisitor18]

Ariunsanaa they are OK. You can use them for simple things. If you plan on going into programming or networking. I would highly recommend you buy a book such as visual C#, VB. Net, etc. Books will be a better start, however these video are educational for the general public.

[@theinquisitor18]

Ariunsanaa no problem. If you are going into computer science. Welcome aboard.

[@Ryosuke37859]

The Inquisitor Unless you plan to work only on Microsoft products, it’s probably better to recommend starting with Python, Ruby, or Go as a first language. Most of the internet runs on Unix / Linux based systems, so VB / C# wouldn’t get you very far without unnecessary headache. I would also recommend reading TCP / IP Illustrated, as it gives a much more thorough (and necessary) understanding of networking that I find many CS / CompEng graduates lacking.

[@keepbreathing7827]

Is mathematics necessary for cs ?

[@moparmagoo]

@@keepbreathing7827 generally speaking, any "Science" degree is going to require some amount of college level mathematics. Computer Science is no exception

[@kristofferbrink2689]

Thanks for all your work Crash Course! It’s amazing that you share all this knowledge for free. All the videos of yours I’ve seen, have been great, interesting, logical, and very informative.

[@crashcourse]

Thank you for supporting our channel!

[@BanditRants]

Decades of research, diligence, industry, and perseverance to conceive networks, and I solely use it for Porn.

[@assertivecunts2341]

HAhahahah same

[@tonyrawmen4966]

You also use it to upload your epic videos, love your channel btw!

[@reaper3569]

subbed!

[@Chomuggaacapri]

AND watch this series!

[@AnnLaustsen87]

Good thing that the content gets to you in the correct order of packets.

[@remuladgryta]

Ah yes, the internet of things. What a beauty! Never before could your juice have DRM or your lightbulbs DDOS someone.

[@valhekouneli5411]

Yesss! I'm just attending a Computer Networking 101 course at my university, so this series coming out has just the perfect timing! :) Thank you! ^^

[@guacamolly_]

You guys are helping me make sense out of lengthy lectures! The visuals help a lot. Thank you CrashCourse!!

[@Ayplus]

This series is great. In under 30 episodes you've summarized 4+ years of Electrical/Computer Engineering classes I took. . .

[@chrissehnert8623]

Chris from Minny-Apolis here....I wasn't gonna mention the mis-pronunciation....but then you did it again....and then.....YOU BLEW US UP IN A MUSHROOM CLOUD!!!!...on the graphic.....now...Carrie-an-Anne....we are good people up here....you should come and see......some pretty impressive computer science history of our own....see Control Data for instance.....Love the series......hope you'll treat my home town a little nicer in the future though....

[@morchellemusic2829]

1 year in 12 minutes, she's a rockstar

[@kd1s]

I remember Bitnet and X.25 and all the other protocols we used to communicate before TCP/IP came about. And now we have big NAS and SAN technologies approaching the Petabyte and further. Oh and the MAC address, first three bytes indicate the manufacturer. You can look it up on google. And regards splitting networks then there are VLAN technologies. And the telephone network - it uses classes of offices, local is a 5, then there are tandems and long distance switches.

[@Drex2580]

I'm actually getting certified for my a+ certification!

[@lAMAR658]

right on got mine in 04

[@lAMAR658]

since you guys are studing why dont you help each other out...q and a style

[@gotatopaming6336]

Congratulations!

[@zephyr5802]

I’m studying for the A+, Network +, and Server+

[@LLL124Original]

@@zephyr5802 Do those certifications actually get you a job?

[@myxxxomatosis2017]

Finally been waiting for this episode since day 1. Very useful for my cisco class! Thank you crash course!

[@vartanshamirian1008]

I think I learned the most amount of information in the shortest amount of time from this video. Like in my whole life.

[@damian1036]

Thanks! This video helped me understand typologies and mac address very well.

[@love-hammer]

CCNA exam materials are a great resources for studying this topic because it's literally certification to prove your expertise in routing and switching. The OSI model is a great way to digest the topic and troubleshooting issues by taking the (cue music) levels of abstraction approach.

[@maryamlina644]

it feels so good when I understand :,)

[@1Learning2Play]

A correct reference to Colossus and Bombe. Nicely done.

[@eswee6780]

a bit of feedback: it is easier if the next 'episode' link is in the description Apart from that, this video explained it really well, good job :)

[@Tourian]

Amazing videos, this series just keeps getting better.

[@budgetingguide]

Great Production.

[@chefhearne]

My poor Minneapolis, first it sounded like our city's name was mispronounced (@7:47 and @8:03) and then we get figuratively blown up (@10:28). Why all the MN hate? :) Good episode, learned a few new things.

[@Jay-qg3bi]

I currently take networking and tech class. this is really good and straight to the point. Good information

[@samuelgide6840]

You are so interesting ,i never see anyone who explains networking more than you you are a hero i wish you have all the semester . now i love networking thank you dear

[@arsemodeus]

Absolutely terrific episode, very much looking forward to the next two.

[@lucaslu6268]

This episode is one of the best ones in the series!

[@miningbot-fu6on]

heads up if you are studying for the ccent icnd1 note: current switches create separate collision domains for each connected device

[@yourbuddyunit]

Watching while procrastinating on my CCNA classwork!

[@MattCurney]

As someone up here in Mpls, I got anxiety when she blew us up with a nuclear attack. 10:30 Still loving every second of this course though..

[@gudgirl_666]

Thank you for this video! I'm a CS student taking data communication this semester and this video helps a lot :)

[@neomashego]

Lol,im writing my computer networks exam in the next 3 hours.This is a good way of quickly revising.

[@bharathdev6285]

very enlightening, great job guys

[@Supersoaker-xy2cr]

YOUR WORK IS BETTER THSN GOOGLE!!!!!!!!!!!!!! omg thank you.. i have been taking the google it course and none of this made any sense until I saw this video..

[@photosinensis]

Quibbles: 1. Wifi does not use air. It uses the electromagnetic field. 2. Transmission Control Protocol/Internet Protocol is built on top of Ethernet, not Internet Protocol. The physical layer is either a wire, fiber optic cable, or the electromagnetic field--it's the thing physically connecting the devices on the network. The TCP is the part that deals with out-of-order and missing data. You can have IP systems that don't use TCP: most video chat services use UDP on top of IP instead, as they are more willing to let the final destination figure out what to do with the out of order/missing packets.

[@gracegarmo999]

I love these videos so much

[@jecelassumpcaojr890]

Just a very small correction: "medium" is what is shared by the nodes and "carrier" is something that can be present in the medium or not. In a ham radio, for example, if you press the transmit button but don't say anything you will be sending a carrier which won't have any modulation but can still be detected. In Ethernet there normally won't be a carrier unless bits are being sent except for a short preamble at the start of a packet.

[@augurelite]

YAY SO EXCITED FOR PART 2

[@EtrielDevyt]

"Decentralized, with no central authority or single point of failure" When the government accidentally helps introduce anarchism to the web

[@terryosborne2964]

I can see what you were saying oh my God the irony but Closed proprietary versus open standards have every single different Hardware communicate on the same network universally accepted Open Standards. Is a hell of a lot cheaper than closed proprietary standards which means extra cause and sometimes you pay for more proprietary Hardware & software patents which helped Decentralized become more successful. As for centralized it has pro and cons big con take out the central hub the entire communication network is down and that's the big advantage for Decentralized Reliable & redundant network It has little to do with anarchism vs statism

[@karen-sl4cd]

Thanks Carrie Ann!

[@XxBattleMan321xX]

Much more effective than my university lectures!

[@loganatkins7878]

I never thought i would have to slow down a video, but here we are.

[@BlueyMcPhluey]

I love this series!!!!!!

[@riyadpatelwrites]

Thank God for Crash Course 🙏

[@TreasureSam-Ogolo]

You lot have saved me during multiple trying times thank youu!!!!!!

[@jaysallis5718]

absolutley love your videos!

[@phlsnst5882]

Really good episode. Learned so much

[@TilmanBaumann]

Casually brushing over the fact that Ethernet is packet switching as well. But I'm not complaining. It's really good lecture for millennials who didn't have to crimp BNC cables and network inadequate Win 3.11 nodes. :D

[@manlreymont3265]

The course is seriously helpful, try check it out on their website. And literally found so many courses. Luvit !

[@feretiuti2550]

I loved the graphics. Super cool

[@jaredbosire1852]

unlocking networking within fractions of seconds.keep it up.

[@brocksprogramming]

Way to go Carrie Anne!

[@twofaces4410]

A semester of 6 months in just one 12 minutes video.....amazing

[@dippy9119]

Great series!

[@IngLauraDuarte]

I love this CC so much!! Thanks! :)

[@monjasonsteng7861]

Thank you for this amazing video. Your explanation is great.

[@GeenaAntunovic]

OMG Carrie Anne, you are officially my favourite presenter on KZbin. I love how sweet and smart young lady you are.

[@joeljohn7401]

You are AWESOME !!!! GREAT JOB !!

[@net81j]

10 Billion Computers? That's more computers than humans. Awesome!!

[@bensmith9253]

That was really good. I especially like the fast pace of delivery.

[@MarSonyTM]

what an amazing video thank you so much !

[@DustinWatson01]

Great series, keep it up

[@StanEclipse]

this course is really great

[@egg2242]

What about Crash Course music theory?

[@hugoiwata]

Great idea!

[@BertGrink]

Agreed

[@csvscs]

Clay Snyder yes please!!!!

[@Raya-xw5ud]

Yes!! I need this so bad!!!

[@trannusaran6164]

That would be awesome!

[@SporkRocker]

You've made me crush by the Randon Access Memories. +1 kudos

[@gmanjr123456]

You're literally a genius

[@John-lf3xf]

This was unbelievably informative and useful! Thanks!

[@Kaizykat]

I'm taking the Google course over at Coursera and this has helped a lot in putting together all of the information I've learned. The Google courses are good, but information-dense without many visuals.

[@leahchan0705]

this just save my life thank you kind youthful lady wearing glasses

[@garrettalvarez2335]

Keep up the Great work I love this show!

[@sushantkarki2708]

4:07 , thank you for a comedy sketch idea

[@nathanlandis1892]

Loved it! Very entertaining and informative.

[@f.osborn1579]

Mini-in-app-olis…nice…the locals pronounce it mini-app-olis…the mini Apple if you will. Great video!

[@dr.mounir.mallek]

03:02 the air carrying wifi ? thats too far of a stretch to be considered correct ! better put a note there. PS : for those who doesn't know, a radio wave (wifi included) carries it self

[@Daniel-fv1ff]

Mounir Mallek I agree. Also wifi transmits data with microwaves, not radio waves. Edit: never mind, microwaves are a subset of radio waves

[@dr.mounir.mallek]

You got me on that one xD i should have said electromagnetic waves in general.

[@IceMetalPunk]

Weeeelllll.... yes, but also, no. It depends how you define "carries". Consider that while light doesn't need a medium to travel, if it travels through one, it's still considered to be carried by the medium, and in fact the medium in which light is carried changes its properties (such as its speed). So... yes, EM waves "carry" themselves, but they can also be considered "carried" by whatever medium they're traveling in. It's all semantics.

[@dr.mounir.mallek]

Well no, you are misinterpreting the facts here. even when EM waves travel through a medium they are not carried by it ! because the medium is just atoms separated by some amount of empty space and light just passes through the empty space until it 'hits' an atom or electron and interacts with it. hence properties of light aren't changed ! the speed of light is a constant and the fact that it takes more time to do some distance through air because it bounced off some atoms won't change that.

[@IkeOld]

Actually, the speed of light is not a constant. We just treat it like that cause it is mathematical convenient to round it off. It also is treated like that cause the most severe deviations doesn't concern us. So it is practical to see it as a constant. This is a crash course, so the more delicate realities are neglected. So saying that it carries over air is no different true then saying the speed of light is a constant. It all depends on the goal of the conversation.

[@akashamouginot8355]

5:24 MY SCHOOL! IT'S MY SCHOOOOOOL!!!!

[@lohphat]

The stopped short when discussing switches. Today, switches separate all traffic between clients so there's no colkisions on the wire by buffering packets in memory and just queueing them up to transmit in turn.

[@MakeMeThinkAgain]

I'm only at 1:24 but I'm thinking this should have been titled, "The Birth of the Age of Cables."

[@hasyimasyarifudin4996]

i like this information, for my education in networking, thank you

[@daggupatikoukar5175]

thanks mam its incredible

[@Roxor128]

Correction: It's not "Internet of Things". That's incomplete. It's "Internet of Things that Should Not Be On the Internet".

[@EdwardCree]

Fact checking! 2:50 No, every (Ethernet) _network interface controller_ ("NIC") made today comes with its own unique MAC address. Admittedly many PC motherboards, SoCs and even embedded systems nowadays come with an integrated Ethernet controller rather than a separate card attached to a bus (such as PCIe), but the MAC address is definitely a property of the interface and not of the host. (Though some Field-Replaceable Unit (FRU) systems like 'SMASH CLP' try to hide that by having the host (or a BMC) override the NIC's MAC address, this is IMHO a really bad design.) 3:03 Others have pointed out that radio waves aren't carried by the air, but Ethernet is not always over copper wire either. Especially high-speed (10G and above) often uses optic fibre. 8:38 Packets don't store their hop count, they count _down_ from an initial Time-To-Live (TTL, though IPv6 does rename it _hop limit_). 9:46 The term "congestion control" isn't usually used to refer to load-balancing by routers, but rather an endpoint algorithm (such as TCP's _Reno_ or _Vegas_) that detects when the network is congested and reduces transmission bandwidth (in the TCP case, by shrinking the transmit window size). This is necessary because without such an algorithm, increases in latency due to congestion lead to excessive retransmits, which multiplies the load and thus increases the congestion - a phenomenon known as _congestive collapse_.

[@geroni87]

5:50 When you say the switch sits between two smaller network, you're describing the function of a router, not a switch. Routers are the one that divide networks. Also if that's indeed a switch, you'll have six collision domains, not two (one per each switchport). 10:40 ICMP is not used to exchange routing information, BGP (among others protocols) is used for that purpose. Lots of info in just that short amount of time, good job! It's a great series!

[@rogejedib333]

Router divide networks yes but switched divide collision domains. Back before the 2000's when switches were still really expensive they were used to divide up groups of computers connected by hubs. it is only in modern networks that it has become cheap enough to connect a switch to an individual computer and allow bilateral communication.

[@talideon]

It's a bit fuzzier than that. People have a bad habit of using the terms interchangeably, and often the very same bit of hardware does the job of a router and a switch, leading to the fuzziness.

[@rogejedib333]

Agreed.

[@jdrasher3]

They're talking about a two port switch. Each set of 3 computers are sharing the same physical cable, they're not confusing switches and routers. The diagram and example are being explained in the context of the very early days of networking. en.wikipedia.org/wiki/Ethernet#Shared_media Also, ICMP is used by routers to communicate with one another, like she said, even though it does not specifically transfer routing information. tools.ietf.org/html/rfc792

[@DeronMeranda]

You didn't even need hubs (which is what this video is describing). It was common to connect groups of computers using nothing but coax cable (10BASE2 Ethernet), so the computers literally were all using the same physical "wire", and for small networks no network equipment "boxes" were needed at all. Hubs were sometimes used to join these groups together for long runs and such, serving mostly as a dumb repeater/amplifier. Switches were initially very expensive, even for a 2-port switch, and so were judicially used to isolate traffic between networks. Of course even before Ethernet came to dominate, there was Token Ring, which had it's own novel way to avoid the possibility of collisions altogether.

[@aaroncondron8419]

WOO! EPISODE 800!

[@benmorris9925]

3:20 - "Alexa, play Nobody Does It Better by Carly Simon"

[@johnbecker3116]

How did you say the name of my wonderful city of Minneapolis at 7:45

[@yaswanthcharan2340]

ur videos are great with that animations