It depends on what you're trying to serve, but it's used to either save you money or as an insurance (or both). You don't need a CDN overall. But if you grow large enough, at some point you'll run into one of these three situations:
- Your public traffic costs you so much to repeatedly process that it's cheaper to let some service cache the common responses instead. (Where the cache size is larger than anything you'd want to support yourself. For example, if it's <1G and survives your service restarts, you may want to do it yourself)
- Your customers on the other side of the world start complaining that the resources take ages to load.
- Someone floods you with enough traffic that you can't respond to real customers traffic anymore. You get a ransom email to pay them to stop. But there are enough groups doing that that paying is useless because someone else will try again in a few days. If you're providing a service where people pay you to use the website, you're losing money until you solve this problem.
Reduces latency when the cached content is served from a local cdn pop, allows you to absorb some level of DDoS, can absorb traffic spikes more easily so infra can be more static, reduces load on server if assets are dynamically generated on the backend but can are cacheable, some senses can lead to simpler deployment as you serve assets from an object bucket, so no need to deal with keeping that data in your cluster, but that's minor.
There are downsides too, cost, over caching, privacy/security perhaps too.
Because an average request would have to travel half the globe, so setting up a simple HTTPS connection would already take a second. That's completely unacceptable for static content.
Not only would transfer be slow, they would also be much more pressing on the network as the request would occupy huge stretches and many interconnects and switches.
Furthermore, it hardens the website against DDoS and adds robustness for regional failures.
Minority of sites have global traffic. This is especially true for non-English sites.
So, while average request may have to travel quarter (not half) of the Internet globe, median request from the set of requests that matter has much lower latency.
Barcelona to Stockholm is about 65ms, ~35ms to Amsterdam, ~43ms to Frankfurt.
HTTP/3 is ubiquitous, you don’t get TCP handshake penalty anymore in major browsers.
If you have a very inefficient backend (maybe legacy project?), you have massive amount of traffic (say 100K req/s or above) or you really must have sub-500ms latency absolutely everywhere in the world, then it might make sense to slap a CDN (or similar) on top of that.
In pretty much any case outside of that, it makes no sense to waste the time, money or effort on CDNs. But, all the CDN companies seemingly have convinced half the internet that you absolutely must use a CDN, otherwise you'll get hacked/broke/killed/sent to the moon, and they've been successful with this campaign too seemingly.
How does a cdn makes you backend faster or your latency better ? I thought it was only for distributing static assets and managing DDOS. If it is for cachable but dynamic content install reverse-proxy cache it will fly.
Because it lets you use it as a geographically distributed cache basically. Most GET requests should be able to be cachable on the typical website, besides the ones that are unique per logged in user or similar.
If your server is in Europe, and you have Australian users, there is a physical limit how low the response times can go, serving bits over that distance, so only way you can make it go below that limit, is by moving where you serve the data from closer to the user.
Lots of websites have horrible performance for whatever reasons, and lots of freelancers/consultants basically default to throwing a CDN on top of those when they get approached by businesses to fix the slow website browsing, as they're not the ones who have to pay the monthly subscription, and the less work they have to do, the better $ per hour spent for them.
I agree that it's a shit solution and there is much better sustainable ways of solving these things.
Your webserver most likely have "rate limiting" built in already, which you can configure to act based on lots of variables typically. Set a limit of 1 req/s or whatever, and you've stopped 99% of all DDoS you'll encounter on the public web. If your visitors get cranky, up it to 10 req/s and you still are preventing most of the "abusive traffic", granted your backend/website isn't completely upside down when it comes to performance and resource usage.
CDN is something you do once you run out of options, not something you should reach for immediately, it makes no sense in most cases of just hosting a website.
This is not how things work and no company providing online services for money would rate limit like that. This would do nothing for real world DDoS. You're in "not even wrong" territory.
And for large services implementing a CDN properly takes days/weeks of preparation. Once you're down it's way too late.
Yeah, of course if you're a large service, stuff that works for SMEs isn't gonna work for you...
If your problem is AI crawlers, then simple rate limits help, I've helped countless of businesses with this already. For the ones that it isn't enough, you continue adding more roadblocks. There is no "one size fits all here" and that you seemingly is under that belief, leads less credence to what you're saying, not more.
It depends on what you're trying to serve, but it's used to either save you money or as an insurance (or both). You don't need a CDN overall. But if you grow large enough, at some point you'll run into one of these three situations:
- Your public traffic costs you so much to repeatedly process that it's cheaper to let some service cache the common responses instead. (Where the cache size is larger than anything you'd want to support yourself. For example, if it's <1G and survives your service restarts, you may want to do it yourself)
- Your customers on the other side of the world start complaining that the resources take ages to load.
- Someone floods you with enough traffic that you can't respond to real customers traffic anymore. You get a ransom email to pay them to stop. But there are enough groups doing that that paying is useless because someone else will try again in a few days. If you're providing a service where people pay you to use the website, you're losing money until you solve this problem.
Reduces latency when the cached content is served from a local cdn pop, allows you to absorb some level of DDoS, can absorb traffic spikes more easily so infra can be more static, reduces load on server if assets are dynamically generated on the backend but can are cacheable, some senses can lead to simpler deployment as you serve assets from an object bucket, so no need to deal with keeping that data in your cluster, but that's minor. There are downsides too, cost, over caching, privacy/security perhaps too.
This article being down/slow is a great response.
Not to discount the experiences that other have, but the site loads fine for me.
Because an average request would have to travel half the globe, so setting up a simple HTTPS connection would already take a second. That's completely unacceptable for static content.
Not only would transfer be slow, they would also be much more pressing on the network as the request would occupy huge stretches and many interconnects and switches.
Furthermore, it hardens the website against DDoS and adds robustness for regional failures.
Minority of sites have global traffic. This is especially true for non-English sites.
So, while average request may have to travel quarter (not half) of the Internet globe, median request from the set of requests that matter has much lower latency.
Barcelona to Stockholm is about 65ms, ~35ms to Amsterdam, ~43ms to Frankfurt.
HTTP/3 is ubiquitous, you don’t get TCP handshake penalty anymore in major browsers.
The site this is about is current down due to HN traffic.
Lol
Depends on your use case.
If you have a very inefficient backend (maybe legacy project?), you have massive amount of traffic (say 100K req/s or above) or you really must have sub-500ms latency absolutely everywhere in the world, then it might make sense to slap a CDN (or similar) on top of that.
In pretty much any case outside of that, it makes no sense to waste the time, money or effort on CDNs. But, all the CDN companies seemingly have convinced half the internet that you absolutely must use a CDN, otherwise you'll get hacked/broke/killed/sent to the moon, and they've been successful with this campaign too seemingly.
How does a cdn makes you backend faster or your latency better ? I thought it was only for distributing static assets and managing DDOS. If it is for cachable but dynamic content install reverse-proxy cache it will fly.
Because it lets you use it as a geographically distributed cache basically. Most GET requests should be able to be cachable on the typical website, besides the ones that are unique per logged in user or similar.
If your server is in Europe, and you have Australian users, there is a physical limit how low the response times can go, serving bits over that distance, so only way you can make it go below that limit, is by moving where you serve the data from closer to the user.
Lots of websites have horrible performance for whatever reasons, and lots of freelancers/consultants basically default to throwing a CDN on top of those when they get approached by businesses to fix the slow website browsing, as they're not the ones who have to pay the monthly subscription, and the less work they have to do, the better $ per hour spent for them.
I agree that it's a shit solution and there is much better sustainable ways of solving these things.
Data scraping.
If anything else, the AI machine wants near constant streams of new data, even if it already checked with you 30ms ago.
A CDN helps immensely.
Also keeps you from getting DDoS'd if you did something like run it off your home connection.
Your webserver most likely have "rate limiting" built in already, which you can configure to act based on lots of variables typically. Set a limit of 1 req/s or whatever, and you've stopped 99% of all DDoS you'll encounter on the public web. If your visitors get cranky, up it to 10 req/s and you still are preventing most of the "abusive traffic", granted your backend/website isn't completely upside down when it comes to performance and resource usage.
CDN is something you do once you run out of options, not something you should reach for immediately, it makes no sense in most cases of just hosting a website.
This is not how things work and no company providing online services for money would rate limit like that. This would do nothing for real world DDoS. You're in "not even wrong" territory.
And for large services implementing a CDN properly takes days/weeks of preparation. Once you're down it's way too late.
Yeah, of course if you're a large service, stuff that works for SMEs isn't gonna work for you...
If your problem is AI crawlers, then simple rate limits help, I've helped countless of businesses with this already. For the ones that it isn't enough, you continue adding more roadblocks. There is no "one size fits all here" and that you seemingly is under that belief, leads less credence to what you're saying, not more.