How a content delivery network works

Is your network infrastructure fast and secure enough to meet the needs of modern users? 

Websites that take 5 seconds to load suffer a 3x worse conversion rate compared to sites that load in 1 second. Whether your site is B2B or B2C, load times are directly tied to revenue. 

Security is another major concern for businesses and users. In a landscape where the rate and diversity of cyberattacks is constantly increasing, the financial and reputational risk is severe. Distributed Denial of Service (DDoS) attacks alone leave companies with an average bill of $408,000 per attack. 

The right Content Delivery Network (CDN) can significantly improve both your online performance and security. Read on to discover how CDNs work, learn about their benefits, and how to choose the best one for your business. 

What is a Content Delivery Network (CDN)?

A Content Delivery Network is a system of interconnected, geographically distributed servers that accelerate the delivery of web content and applications. CDNs are capable of distributing both static and dynamic content to the user from the network edge. Static content could be images, graphics or HTML files, while dynamic would include product recommendation screens, stock tickers, weather widgets, and any other frequently changing content. 

Although the name “content delivery” suggests that these networks might be able to replace web hosting, that is not the case. Instead, CDNs function to enhance rather than substitute web hosting services. CDN servers do not host versions of the site or app but, instead, cache temporary copies of the most frequently accessed content in locations that are geographically closer to visitors. This geographic distribution supports enhanced speed and security. 

How does a CDN work?

CDNs work by distributing content across globally distributed servers, caching data at these edge locations (servers placed near end-users globally), and routing user requests to the nearest server to deliver content quickly and efficiently. 

Apps and websites can use a CDN in a way that is similar to how online retailers use regional warehouses. Retailers could deliver products straight from the factory to the consumer. However, by storing goods in warehouses located close to their customers, they can offer significantly faster delivery times. 

Most CDNs offer a set of key features that include:

• Content distribution: CDNs have a presence at Internet exchange points (IXPs), massive physical data centers where network switches route global traffic between the major Internet Service Providers (ISPs). Having connections to these extremely high-speed exchange points is key to providing rapid data delivery to users. Many also have additional smaller, distributed servers to augment their service.

• Caching: Temporarily stores copies of frequently accessed content for faster retrieval, while leaving the original content intact at the origin.

• Request routing: Guides user requests to the best-suited server based on location and network conditions. 

• Load balancing: Allocates traffic across several servers to avoid overloading any single one, increasing reliability.

• Origin shielding: Protects the host server from excessive requests by routing through intermediary servers.

• Content optimization: Compresses and modifies static content, such as images, HTML, JavaScript and CSS, for faster delivery. This involves lossless techniques like Brotli and also minification, a process in which code blocks are reduced in size by eliminating comments, whitespace, and descriptive variable names.

• Infrastructure optimization: The best CDNs let you take advantage of advanced, energy-efficient servers and data centers equipped with solid-state drives (SSDs) without you having to invest in new equipment. 

• Real-time analytics: Involves monitoring performance and user behavior to optimize content delivery.

• Security measures: Provides enhanced protection against DDoS attacks and other threats.

• Content invalidation and purging: If cached content isn't properly invalidated or purged, outdated data may still be served to users despite changes in the underlying data. Purging can be done manually or automatically, with strategies like full, partial, or smart purges to balance content freshness and performance. 

• Intelligent failover and redundancy: Ensures service availability during server or network failures. Fastly's Autopilot and Precision Path technologies efficiently manage network traffic by automatically rerouting around failures and optimizing paths, enhancing reliability and performance. This approach ensures seamless service during unexpected traffic spikes or network issues through rapid rerouting and informed long-term decisions.

The CDN content delivery process

To decide whether a CDN is right for your business, it’s important to understand the step-by-step process of how these networks deliver content. When performed correctly, this system can deliver impressive results for both website performance and user experience. Here’s a behind-the-scenes look at how CDNs optimize websites and applications on an interaction-by-interaction basis:

• User request initiation: The user enters a URL or clicks a link to access content.

• DNS resolution: The domain name system translates the domain name to the IP address of the closest CDN server.

• Request routing: CDN's load balancer directs the request to the most suitable edge server. This is often based on geographic proximity, server load, and network conditions. Distance reduction typically equates to a lower round-trip-time (RTT) for requests, increasing overall speed. 

• Edge server check: The server checks whether the requested content is cached and valid.

• Cache hit scenario: If the content is cached, the server serves it immediately to the user.

• Cache miss scenario: If content is not cached, the edge server retrieves it from the origin server.

• Host response: The origin server delivers the requested content to the edge server.

• Edge server caching: The server stores the content to fulfill future requests.

• Content delivery: The server sends the requested content to the user's device.

• Performance monitoring: The CDN logs and analyzes the transaction for optimization.

The top 8 benefits of using a CDN

Above all, geographically distributed caching and routing lead to improved user experience, enhanced performance, and increased operational efficiency for any business that runs a website or online application. But there are additional ways a CDN can help your company thrive. 

Here are the eight advantages of having a CDN:

Accelerated content delivery: A CDN reduces latency and boosts page load speeds for users worldwide.

Reduced server load: Transfers traffic from origin servers to distributed edge servers at points of presence.

Enhanced website availability: Provides redundancy and failover capabilities to minimize downtime.

Improved security: A CDN’s distributed architecture increases security, making it difficult for attackers to overwhelm the network with a DDoS attack because traffic is spread across multiple locations, reducing the impact on any single server or data center. Other security features like rate limiting and traffic filtering can control data flow and prevent malicious actors from accessing critical data centers. 

Optimized SEO performance: Enhances page speed and user experience metrics for better search rankings. 

Better scalability: Manages traffic spikes and growing user bases without infrastructure changes.

Valuable insights: Delivers analytics and reporting for performance monitoring and optimization.

Lowered costs: Reduces bandwidth expenses and infrastructure requirements for content delivery.

Why Fastly stands out as the best CDN provider

Your online applications and websites deliver the most return on investment when they can efficiently serve a global audience. Meeting the needs of that worldwide user base requires a powerful Content Delivery Network. 

Fastly’s CDN is the next-gen delivery network enabling enterprises to expand their global presence. 

Among its many advantages, Fastly offers:

• Global edge network: Fastly has strategically located Points of Presence (PoPs) with high capacity.

• Real-time purging: Fastly's Instant Purge™ and soft purge features enable more control over the caching of dynamic content and quick content changes that propagate across the network.

• Edge computing capabilities: Edge computing enhances CDN functionality

• Advanced caching strategies: Fastly's flexible VCL-based caching ensures efficient management and control of traffic within a domain.

• Real-time configuration: Our network provides developers with real-time configuration control, comprehensive APIs, stress-free rollbacks, and real-time logs, enhancing workflows and reducing reliance on professional services. It integrates seamlessly with CI/CD cycles and DevOps tools enhances workflows and increases developer satisfaction. Fastly offers unrivaled control and configurability through an intuitive UI or flexible API.

• Streaming optimization: Support for low-latency live-streaming and dynamic ad insertion.

• Optimizes images: The CDN compresses and optimizes your images on the fly without losing quality.

• Shielding: Designate one POP location as a 'shield' to decrease the load on origin servers and enhance the cache hit ratio, and speed up connections by minimizing latency for requests.

• Security features: Fastly’s DDoS protection, Next-Gen Web Application Firewall, and Bot Management protect applications with intelligent detection and mitigation strategies to prevent resource abuse and ensure enhanced content security. 

• Real-time analytics: Comprehensive logging and insights for performance monitoring and optimization.

Discover what Fastly’s Managed CDN can do for your website or app by signing up for a free trial.