Savor the use of CDN

CDN (content distribution network) is a widely used product. With CDN, we can speed up access to our website nationwide and optimize our user experience.
But we have a love and hate relationship with CDN. We love it because it improves our website experience, especially for some SaaS providers who benefit from CDN to solve static file loading issues.
We hate it because if improperly used, CDN easily causes many problems which may even result in website faults, such as persistent login failures.
 
At the same time, the numerous configuration items of CDN also dazzle us.
Here we provide two diagrams to help you better understand the working principle of CDN so as to use it better.
 
 
Having looked at the diagrams about CDN's working models, I wonder about your thoughts?
I sincerely invite you to share your CDN experiences. You share your experience, and I give you a gift.
You can also raise questions here.    
How to use CDN effectively?
How to use CDN to work in concert with other cloud products?

For example:
I am an SaaS provider and I use CDN for static file acceleration. CDN frees me from worrying about static file traffic problems for my main site, enables me to focus on handling business logic, and, more importantly, makes my users nationwide feel that my website is very fast. It helps me to attract a lot of users and is superb.

Or
I am a web master of an industry forum. There are a lot of resources in our forum and downloading requests come from across the country. I didn't have so much bandwidth so I chose CDN to cache my content. In combination with OSS, CDN enables high-speed downloading nationwide.

I have been using Alibaba CDN and I would like to share my experience. My blog website is powered by WordPress and implements HTTPS. So CDN listens to Port 443. Remember to upload the certificate and enable the secure acceleration mode. Use default settings for the access mode, and force redirect to HTTPS is not recommended. Tests showed that 301 redirect for Port 80 is useless. You can use HSTS and HTTPS domain names. In terms of optimization, I recommend you enable page optimization and intelligent compression. If you use HTTPS only, you don't need to select back-to-source with the same protocol. If you use Port 80 and Port 443 at the same time, enable it. Do remember to use the NotFound Project page for 404 pages! To enable filter parameters, do figure out which parameters the website will use first, and then add exceptions. Otherwise, the website may not be available.

We are a commercial live broadcasting company, but we are not having activities every day. You must have an idea about the traffic usage of live stream media. I think I am probably one of the earliest customers of Alibaba CDN service for streaming media. The daily traffic of a large-scale activity may amount to several TBs, and the peak bandwidth is several GBs, which is clearly different from traditional web sites. Just a few days ago, we broadcasted a commercial performance participated by Li Yuchun and Wang Feng. Setting aside the concurrency, the peak bandwidth amounted to 2.4 GB. If we set up our own servers, the cost would be tens of thousands yuan, with countless technicians required. The 1G bandwidth for a year would cost 120,000 to 300,000 yuan, which is just too much to handle. But we used cloud-based CDN, saving at least a million yuan. Those who have tried it will feel its benefits. The key is the ease of use and the ease of good use at the same time. I recommend you perform proper authentication, for obvious reasons.

I am kind of a small web master. My website has low traffic but I want to learn more about related technologies.
1. I use Qiniu storage service for images and files, and CDN for a sub domain name.
2. Given the high cost of ECS bandwidth, I use Cen to perform CDN for images and downloaded files first to solve the bandwidth issue.
3. The avatar is usually powered by a specialized service provider. But the known common service providers are located overseas and image access is rather sluggish, so I want to use CDN back-to-source function to get the source addresses so as to accelerate the display speed for user accesses, and appoint a sub-domain for it.
4. Many people are suggesting accelerating the site loading through CDN by separating the pages, JS and CSS content. It turns out effective, but it is pity that it is mostly achieved relying on the plug-ins by others, and a sub-domain name is also allocated.
5. We often see red alerts on the console page. After clicking on it, the page will jump to Alibaba Cloud Security page listing so many various items such as **upload vulnerability**, **code/command execution**, and **others**. There are several items every day. Does it mean that my server is under attack every day? I cannot stand it. I must perform CDN for the entire website. So I bound my primary domain as a CDN accelerated domain.
I asked my friends in a technical group about how this can happen. They told me that most of them are actually sniffers, like searching your servers for any vulnerabilities needed by someone else or downloadable files. They are not attacks, Aha.

Do remember to set the most basic anti-leech function when using CDN. Otherwise the consequence would be severe.
But even if you have set anti-leech, the risk remains.
Unless the signature mechanism is also configured.
In addition, remember to perform some processing on the origin site. Do not provide everything to CDN. Otherwise, the cost will rocket if your links are leeched.

Question:
1. Can CDN be used if the website enforces HTTPS?
2. It is previously mentioned that our CDN will retrieve data through the cache at the second request to accelerate the process. But it is very effort-consuming to implement back-to-source for a dynamic website. Does it mean we still mainly implement the static JS and dynamic applications are less demanded for individual web masters?
3. In addition, how is the traffic usage calculated if our website is under DDoS attacks?
4. I used CDN once on an educational website that I set up myself. But it turned out that only static pages can use it, at satisfactory speeds, and the parts of dynamic response cannot be loaded. Later I found Telecom networks cannot be accessed, but the networks of other operators in other regions work. I performed the tests using the agent pages. How should I configure the settings to make CDN available for all the networks of the three major operators?

Blanche：Question:
1. Can CDN be used if the website enforces HTTPS?
2. It is previously mentioned that our CDN will retrieve...回到原帖

1. Yes, it can.
2. It focuses on the static JS, and won't accelerate dynamic content.
3. If your website suffers DDoS attacks, part of the traffic will be charged, and the rest part will go through the cache. It is dependent on your cache settings.
4. Alibaba Cloud CDN is actually available for the networks of all operators. If an unavailable node appears, you can submit a ticket to request a repair.