What is a CDN and Why is it Needed?
A CDN (Content Delivery Network) is a geographically distributed infrastructure of servers that store cached copies of your web content. Instead of every user request going to a single central origin server, the content is delivered from the nearest edge server to the user. This significantly speeds up the loading of websites, videos, and other content, reduces the load on the main server, and improves the overall stability of the resource.
The primary goal of a CDN is to minimize latency in data delivery. But beyond speed, modern CDN networks solve other critical tasks: they help withstand high peak loads, provide resistance to DDoS attacks, and make infrastructure scaling simpler and cheaper.
How It Works: The Role of DNS, Servers, and Caching
When a user enters a website address in their browser, the process begins with a DNS request. When using a CDN, the DNS system plays a key role. Instead of simply returning the IP address of your main server, the CDN provider’s DNS server analyzes the user’s location and directs their request to the nearest and least loaded edge server in the CDN network.
If a cached copy of the requested content (like an image or CSS file) already exists on this server, it is delivered to the user instantly. If the content is not in the cache, the edge server contacts your origin server, downloads the necessary file, saves it to its cache for future requests, and then transmits it to the user. This process ensures fast content delivery and reduces the load on your main infrastructure.
CDN Reliability: What If Something Goes Wrong?
Despite all the advantages, it’s important to understand that no system is immune to failure. Even industry giants like Cloudflare can face problems that affect a huge portion of the internet.
“We’re seeing how few of these companies there are in the infrastructure of the internet, so that when one of them fails it becomes really obvious quickly,” noted Professor Alan Woodward of the Surrey Centre for Cyber Security .
This situation highlights the modern web’s critical dependence on a few major players. When a CDN-level outage occurs, it can lead to the unavailability of thousands of sites at once. This forces us to think about diversifying risks and having a backup plan.
Urgent Update: Global Cloudflare Outage on November 18, 2025
Ironically, on the very day this article was being written, November 18, 2025, Cloudflare error occurred and Cloudflare experienced another major outage that once again paralyzed a significant part of the internet. The problem, caused by an anomalous traffic spike, affected services such as X (formerly Twitter), Spotify, ChatGPT, and many others. Users worldwide encountered errors, and Cloudflare’s official status page confirmed an “internal service degradation”.
This real-time incident serves as the most vivid confirmation of the fragility of centralized internet infrastructure and the need for risk diversification for any serious online project.
Cloudflare Alternatives: Who Else is on the Market?
Although Cloudflare is one of the most popular providers, there are many strong alternatives on the market, each with its own features. The choice depends on your specific needs, whether it’s a focus on security, price, or specific technical capabilities.
| Provider | Key Advantages | Pricing Model |
|---|---|---|
| Sucuri | Comprehensive security, WAF, free malware removal | From $229/year |
| Bunny.net | High speed and affordable prices | Pay-as-you-go |
| Amazon CloudFront | Scalability and deep integration with the AWS ecosystem | Pay-as-you-go |
| Fastly | Real-time caching, high performance for enterprise | From $50/month |
| Akamai | One of the oldest and largest CDNs with a huge global network | Custom |
| KeyCDN | Simplicity and low cost | Pay-as-you-go |
Advantages and Limitations of CDN
Main Advantages of CDN:
- Speed: Users receive content almost instantly.
- Reliability: Reducing the load on the origin server increases fault tolerance.
- Security: Filtering of malicious traffic and protection against DDoS attacks.
Limitations:
- Cost: Commercial CDNs can be expensive for high traffic volumes.
- Dynamic Content: A CDN is less effective for pages that are generated individually for each user.
- Centralization of Risk: An outage at a major provider can affect many resources.
Conclusion
A CDN is a powerful tool for improving the speed, security, and stability of your web resource. It helps provide users with fast access to content regardless of their location. However, recent events show that blindly trusting a single provider, even the largest one, can be risky. When choosing a CDN solution, it is important not only to evaluate its performance and price but also to consider alternatives and develop a strategy for potential outages.