What is a Content Delivery Network (CDN)?

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A content delivery network (CDN) is a distributed server network that accelerates internet content delivery to users based on their geographical location. This will help improve both your users' website experience and reduction in bounced sessions.
Check out this quick overview video with Ryan Sumner as he goes through a scenario where CDN helps make the website load time faster for globally distributed users.
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#ContentDeliveryNetwork #CDN #Networking

[@atmospheric_b]

half of the video i was thinking about the setup of that mirror board you are writing on))) Thanks

[@Dennis_315]

I initially thought he was writing backwards perfectly, but then realized the's writing on a glass pain and the image is just flipped. Ok, that's done, i can concentrate on the video now.

[@IBMTechnology]

Here's a post we wrote to explain how these videos are created. kzbin.info/door/KWaEZ-_VweaEx1j62do_vQcommunity?lb=Ugzf5SL_yh9NglCJzgF4AaABCQ Let us know if you have any more questions and thanks for visiting.

[@desmondamberetu4345]

me too, i thought i was the only one

[@richiemello3447]

This is how you truly know if your a nerd. Spends more time wondering how something works instead of just listening to the video lol

[@ashwath2324]

Same here...I thought it was shot from behind and added that layer...anyways that's clever

[@brooklynnsumner7598]

go dad!! super proud!

[@IBMTechnology]

Thanks for watching Brooklynn! Your dad did a great job.

[@TheCameltotem]

Your dad is great at explaining!

[@jjll6745]

IBM Cloud dad can you explain load balance vs cdn. it sounds like they are the same??

[@spacejam22]

wait a second he looks so young

[@goofygoober1009]

that’s cute :)

[@user-fe3uy3zd6b]

Thanks for the quality explanation! Already tested CDN Serverspace, content download speed has increased by 1.5 times.

[@RajibBiswasurl]

Mr. Ryan, thank you very much for the simple explanation..

[@lambmaster27]

Great video! Thanks for making it! Very quick, simple, and informative!

[@ChocolateMilkCultLeader]

The perfect video on this topic. Crisp and covering the right details

[@thomas-sinkala]

Straight to the point. I love this.

[@alekssad2543]

Great video! Simple and exact explanation. Just what I needed. Thank you!

[@ajmalosmani79999]

Very concise and to the point explanation, Thank you.

[@MemeSaad86]

simple, direct to the point, perfect. thanks

[@poultryfarmchicks123]

Thanks for the explaining Details about Content Delivery Network...

[@ishaanniyazi7624]

Easy and Simple way to understand the need of CDN Thanks sir

[@leventinaglans5425]

Very clear! Now I know what is it. This lesson should be in YT's top by query "CDN dns"

[@aaronharris2144]

thank u for this great visual!! so easy to understand!

[@Ashish8363]

Amazing explaination and ability to write mirror words. You're a god.

[@ravik7734]

Crisp and punchy.. well done!

[@prudhvin9730]

this is simple and amazing explanation.

[@emaxv1979]

Grear video Ryan! (And mirror board) Thanks!

[@naumanahmad5254]

Very simple and better explanation. Love from Pakistan

[@marketingsale3543]

Thanks for the useful information that I am actively learning about CDN.

[@Sneguro4ka]

That... was...an... awesome.... explanation.

[@monjasonsteng7861]

This was great. Thank you so much for the fantastic explanation.

[@djdc81]

This was super helpful for a project. Thanks.

[@cfanaticrekords7767]

I really understand CDNs now, thank you to much.

[@josephgibbons1195]

This explanation was exactly what I needed! Thank you!

[@IBMTechnology]

This is great to hear, Joseph!

[@aaronmarco6077]

Well Explained.....CDN helps to accelerate the website and delivers the content to the users in all global locations.

[@IBMTechnology]

We appreciate your positive comments, Aaron. Thank you for checking out our channel.

[@quiccloud]

Great explanation on how CDNs like ours work. Thanks

[@jimoblert5972]

Perfect explanation video. Just basic facts in words that everyone understands. Great job 🔥👌

[@IBMTechnology]

Thank you!

[@jimoblert5972]

IBM Cloud You're welcome

[@haseebkalwar2759]

Great Video, Very Informative and well explained

[@ArmenBabakanian]

This is a great video, just a small clarification I think you should point out - when you say website runs faster it might be misleading, CDN will make your website load faster - the website itself might be doing some heavy javascript calculations which with or without a CDN, that part would not be impacted.

[@rob5381]

thanks for the video makes it more understanding why an cdn would be good to have for websites

[@IBMTechnology]

Great Rob, glad to hear!

[@AbhinavKumar-dr4ef]

Thank you for the visual education.

[@vmandalapu1994]

Great video! Have one basic question. How the request goes to CDN instead of actual server? because DNS server resolves the hostname to IP addess of actual server right?

[@fabian-manzano]

Nice video, I dont get why people will down vote this great explanation :)

[@jeffrygunawan3328]

thankyou sir... your explaination is very well

[@teus8753]

Thank you, simple yet informative

[@IBMTechnology]

You're welcome, thanks for watching! 👍

[@loladaryanto822]

Omg thank you so much that was so helpful!

[@dkinyua7]

A very good video; thanks for sharing that info.

[@ateeqahmad]

This is so good. I am going to use it to explain CDN to my class. Makes my lecture irrelevant!!! Thank you!

[@eminberkay]

Great explanation, thanks a lot!

[@AmanKumar-hr5dc]

Great Explanation!

[@FirstLast-qy7hf]

Imagine being able to write backwards in a mirror like way, and explaining this stuff, really God job

[@AwaraGhumakkad]

thanks for such an amazing video - few questions may be dumb sorry about that 1. who installs the CND? 2. whose responsibility is to maintain CDNs? 3. every company places there own CDNs? 4. companies has to pay to someone for CDN? 5. If responses are saved in CDNs from actual server- suppose the content of an Site changes then how will it reflect to users ? because response is already cached in CDN ? so my question is how long CDN keep serving through itself ? when does it refreshes itself with current actual server data

[@muhammedladeed2280]

yeah. i also have these doubts bro .did you get the answers for these?

[@blasttrash]

I think there are dedicated CDN companies like Akamai, CloudFlare, Google DNS etc. So if you are a company owner, you could pay and use these services. These services usually have a dashboard where you can upload content. This is called a push CDNs, meaning you are pushing data. Some of these services also provide APIs, so you don't have to manually open their dashboard and upload HTML, videos etc. Instead in your code, itself you can have sophisticated logic to upload and distribute newly added content across the globe. However some of these services also have pull CDNs wherein it works like a LRU(least recently used cache). Say your first user request for HTML page, that request goes to your server and that data is cached in pull CDN. From next time, that user can directly hit pull CDN instead of making round trip to your server. On the other hand, if you don't trust cloud services, then you as an owner can also create your own CDNs. Some big companies do it all on their own and maintain their own servers. Or some companies like Netflix what they do is, they partner with other CDN companies and ISPs(Internet Service Providers like Airtel, Verizon, Jio etc) and store videos etc right there. So whenever new content gets added to Netflix you don't have to to USA to get that data for example, but your ISP or some nearest CDN can give that information for you. And for all of this data, there is usually something called TTL(Time to live). its like a expiry date. Usually in hours or days or seconds(for some dynamic content). You should be careful while setting these values coz your users might end up getting stale or old data depending on how large your TTL values are. This is also where cache invalidation becomes important. Like what strategy do you use: LRU, LFU, Random etc.

[@saraeissa4954]

@@blasttrash are CDN company rates affordable for startups with no money?

[@anujoza]

firstly thanks for the great info ...I have a question which might sound naive...but what happens when you update even static content say from your example and deploy those changes to your host server i.e. Dallas server how will CDNs around the world will get an updated copy ? is there a specific mechanism for it to let the CDNs re-fetch and create a new cache ?

[@shaoboliu1109]

Thank you for the short but straightforward explanation of CDN. My question is, what's the difference between using CDN and setting up servers in different geo locations? Does the 2nd way also solve the problem CDN solves?

[@himachal8252]

I think the difference may be that CDN contains only some specefic data that's same for all users but if we set different server it needs to have exact copy of each other for consistency in other words a whole lot of data need to be stored

[@harshpandey6799]

Setting up different servers at different location would be costly. you may need to replicate entire system (services/databases). It will increase cost and adds consistency issues. Whereas the CDN here is requesting from the same server as was done before adding CDN.

[@shivaprasad098765432]

@@xjsonx Yes Json, CDN does cache data. Only when a new request is done to the edge node it communicates to server to bring it and also store it for subsequent similar requests

[@rapsysinfotech1309]

how you are writing on screen , it's interesting .What technology you are using ?

[@snowleopard285]

Does that mean that the content loading speed is exactly the same, compared to hosting it locally? E.g. if I host a website on the origin located in Dallas, and the consumers of my content are located in Sydney and access it from Australia via a CDN point-of-presence, will the loading speed of my website be the same as if I hosted it on a local server or is there any degree of slowness?

[@vincent3542]

legend says, a master can simplified a complex concepts, and now i see the truth.

[@LiamNickell]

How does a CDN cache work? Is data cached in main memory at the edge server or in the server's database or both?

[@_MAHFUJHOSSAIN]

Nice explanation

[@arunparthasarathy]

neat presentation

[@yagizzhn]

The IBM Cloud CDN seems interesting. Also, I am happy to see a partnership with Akamai. I have seen too many websites use Akamai but not so much that uses IBM Cloud CDN. Do you have any tutorials or test files about the IBM Cloud CDN?

[@CheevoCheevo]

I agree, it's a pity that the price is too high. There are offers with CDN cheaper

[@user-zq1ww3hy4f]

thanks for the great expliain

[@ButterySkater]

What about 4k 60fps vs 720p 30fps. Will higher resolution slow down the server or would it all depend on your internet?

[@earthcitizen7156]

what is the diffetrnce bewteen proxy servers or datacenters on different zone and the CDN ? Explain proxyservers vs datacenters vs CDNs ?

[@vineeth7424]

this is awesome

[@faresk3168]

What if the Dallas website gets updated with new content, how and when do the CDN endpoints fetch the new updated information/content?

[@leking1979]

Thanks the video was good and well explained.

[@IBMTechnology]

We are glad that you enjoyed the video. Thank you!

[@vladyslavthegreat3879]

So, the data is not streamed but stored in the closer host. And how we can be sure that the host is secure and trusted?

[@ahmadyounis6814]

Thank You

[@ayanantachowdhury9105]

Well explained

[@ManojLikeSteveJobs]

Thanks:)

[@bryanperalta3885]

great video! 👍🏾

[@EmmanuelOuzan]

Great video, I love that board as well. I understood the problem, the solution benifits, but no the solution itself. What do you mean by endpoints? Are these new servers that are located in every different region?

[@IBMTechnology]

Hi Emmanuel! For more details about IBM's CDN solution please access the link in the description of this video. And an endpoint in the CDN context is any physical device that's at the end of that specific network and communicates with it back and forth: laptop, mobile phone, router, tablet, server etc.

[@rangermaverick85]

Nice but you should explain more what do you mean by "service". A CDN is a network of interconnected servers/data centers. Content is stored on CDN servers geographically closer to the users

[@TuvRaz]

Very clear

[@sameershahiddd]

Great video!

[@vomitjoe]

Great video! Was wondering if copies of the database are hosted on the CDNs as well, or if CRUD functions still need to make that round trip.

[@IBMTechnology]

Great question, Joel. CDNs are usually implemented in a way that accelerates static content. Static content doesn't usually change frequently, so it can be cached easily by a CDN without there being a risk of the consumer getting stale content. This doesn't mean that you cannot cache dynamic content that is served by a database, but when pushing this content through a CDN, you have to be conscious of presenting stale content to the user. You will need to put more thought into how long you cache that content and even taking additional steps of purging that content from the CDN at the time you create, delete, or update pieces of it. Thank you for watching!--Ryan

[@BikasKatwalK]

Have a few questions? How the browser in Sydney is getting the IP of the Sydney server/edge? How DNS servers or ISPs resolve the correct edge? as one single domain(configured by Akamai) is mapped to multiple edges.

[@jkoorts]

If you find a webpage or a video that technically explains how a CDN works please let me know. This video like others is not it.

[@dadiramya278]

To the Point!!!!

[@Jbyss]

finally i understand what Fastly does lol. thanks

[@psychurch]

So if we have 1TB hosted in Dallas, CDN copies this TB to all of its nodes across the world? So if there are 10 nodes the CDN is hosting 10TB? Im looking to host music albums and allow users to upload their own music as well as download others. Would CDN distribute the entirety of what im hosting to all of its nodes or is it limited to albums that have previously been downloaded by someone at a specific location. If latter is the case, would that mean that the first person to download an album at a distant location experience slower downloads and each subsequent person downloading the same album in the same location would get it faster?

[@rakeshrp8487]

When a user makes a content request, that first goes to the root server? then the root server directs the user(via DNS response i think?) to the nearest node to the user to serve the request? Wanted to understand how does it work or the path followed when a user makes a request?

[@RaviSingh-fv4sh]

If I upload a video, will it get stored in multiple servers?

[@kvelez]

Great video.

[@AbhikalpUnakal]

Basically a torrentesque network with a guaranteed minimum of (x) globally distributed seeds (CDN boxes). Seeds optimize high uplink. During low request rates use high downlink to fetch most frequently cache missed data.

[@Yetipfote]

them backwards writing skills are out of the charts!

[@IBMTechnology]

Well actually, we don't write backward. Here is a blog post we wrote that explains how we do it. ➞ ibm.co/2LTPMjo

[@rajarshibarman4474]

So basically a cdn (eg: CloudFront) located in edge locations in proximity of users all around the world is used to cache conent from an object storage (eg: s3) for faster delivery of static content (eg: images, videos) right?

[@geekmuralin]

Please make full detail video on CDN.

[@akshayrameshwar4869]

i didn't know zack efron can teach cloud computing Awesome tutorial though

[@genlorobdianela5533]

Can CDN be implemented even though it is not REST API compliant? What are the prerequisites implementing this service?Thanks

[@jayak3768]

I am not sure if this video covers basically how the request from the user is intercepted. The request is for the server , how does cdn intercept this request and does not send it to server.

[@andreyvalverde4780]

Awesome video

[@timmycoates]

Are the content delivery end points placed in IBM Cloud data centers around the world? Or are they placed in other locations to ensure they're close to the end user?

[@IBMTechnology]

Hi Tim! So CDN endpoints reside in 180 cities around the world and reside at the edge of IBM Cloud data centers with shared peering connections where applicable to reduce latency between the endpoint and the origin. Thanks for watching! -Ryan

[@gosilankrishnan8025]

Nice video, but I have a question regarding SEO and CDN. Using your example, if say the CDN has a server to host your website in Australia, Sydney users would definitely benefit. But, when Google crawls the internet and comes to that CDN server in Australia, will it recognize your website as a Dallas (US) based website OR will it start thinking that your website is Sydney (AUS) based website? Will local SEO get affected? Thank you!

[@IBMTechnology]

Hi Gosilan: The CDN service would provide Google the closest possible endpoint to its source when its doing the crawl. CDN services don't typically differ in how they provide the closest endpoint to bots, APIs (or crawlers in this case) or real human visitors of the sites. SEO and how its affected by globally distributed content (with or without a CDN) isn't really the nature of this content. Thanks for watching! Ryan

[@robertclive2858]

Thanks

[@kaushikdr]

If we have a request from London, and all the data in all the endpoints is the same, why access it from Sydney (which is further away)? Why not just access it from the London endpoint?

[@acsoribello]

Who handles the content once it is distributed to the locations near the users?

[@workingTchr]

I tutored math one-on-one for many years and got the hang of writing upside down. Some people never realized what I was doing and others were blown away by it. Actually, READING upside down was harder than writing, and as I see you look around on the screen in front of you, it seems like you're having the same trouble! Ah, what we'll do for education...

[@louisconstant8214]

He's writing normally; there is a mirror at a 45 degree angle between the glass he's writing on and the camera, fwhich flips the image. Notice that most people in these videos appear to be left handed when in fact most people are right handed.

[@raihanmdsiqbal9097]

Super video. Are these videos part of some courses? If a whole course made this way it would we awesome to learn. Thanks ibm for this video.

[@IBMTechnology]

Glad you enjoyed it, Raihan! 🙂 And yes, we could say these videos are part of larger courses. This particular one is part of our "Cloud Networking Explained" series. You can head over to our IBM Cloud channel and see all the playlists there.

[@raihanmdsiqbal9097]

@@IBMTechnology . Certificates courses??

[@IBMTechnology]

Well no. 🙂 You can look at these series of videos as larger video courses that you can take for free, at your own leisure. But if you're looking for more in-depth certificate courses, you can check out our IBM Cloud education resources 👉 ibm.co/39L8ZQi or the ones on Coursera 👉 ibm.co/3fKB2Dp What exactly would you be interested in?

[@raihanmdsiqbal9097]

@@IBMTechnology . This kind of explaination along with labs will change a lot of student lives and knowledge. Just Impart knowledge. If there is any sources or full courses like this or if any future course is launched please do make a video and post on the channel. Is there any devops program offered by IBM. I have good gpa but I am looking to upskill myself. Please do Inform me.

[@mrkannanb]

👍🏼

[@marottamonster]

So, if I follow the explanation presented by Mr. Sumner, the assumption is that all of the remote sites are all part of the same organization, and ultimately would all need the content that was requested by the London site [at some point in time] in the near future. So I guess my question is what if all of the sites, being part of the same organization don't actually need the content requested by the London site, then what happens? Is the material still distributed to these end points and held there for a fixed interval of time and then discarded or what? And assuming that the content is requested by site #1, and there are no other sites that are part of this organization, do you still distribute the material to multiple end point locations? I assume not, but I wanted to ask anyway.

[@IBMTechnology]

HI Bob! Each “location” in this video represents both consumers of the content and the closest CDN endpoint or point-of-presence which aren’t necessarily mutually dependent of one another. Since CDN services typically provide accellerati of content destined for the Internet, the consumers are both anywhere and everywhere and the CDN endpoint location availability are relative and specific to the CDN provider. --Hope this helps, Ryan

[@hadjhadji3818]

I forgot what was the video about when i realized that he's writing in reverse so it's readable for us

[@abhijitbanerjee8326]

so how does the Client's DNS resolver route it to the POP server ips? Usually the DNS resolver will point to the web-server / load balancer.

[@IBMTechnology]

Hi Abhijit! CDN implementation usually involves delegating or referring some DNS resource record (ie. CNAME) to the CDN service for ease of integration and implementation. Thank you for your question, Ryan

[@SZ-ZS-]

hey there, are AWS edge locations a CDN? When used with cloud front

[@IBMTechnology]

Hi Conorsz! AWS Cloudfront is a type of CDN, therefor we recommend reviewing which locations edge services are available through their catalog and/or documentation. Thanks for watching our videos. -Ryan

[@SZ-ZS-]

@@IBMTechnology awesome! Thanks for responding. :)

[@xoca7171]

What about the limitations?

[@samarthnarayan3291]

What do you mean by Security by obscurity?

[@adityamishra7614]

Is distance is matter in CDN🤔

[@MorrMedia1]

How is this different than simply adding more localized servers?

[@Placesandspaces35]

So does someone only need a cdn if they are hosting a website? Does it benefit the viewer if they use a cdn for watching live television?

[@IBMTechnology]

Thanks for your question. Some CDN services do provide the ability to accelerate media streams, however the publisher of the content would need to utilize that service and then the consumers of that content would likely benefit. Thanks for watching our video! -Ryan