What Is a CDN (Content Delivery Network)?

A content delivery network (CDN) is a connected group of servers that helps cache and deliver content to users nearby.

A CDN is an architecture of connected servers that deliver content quickly to users around the world. The infrastructure uses servers that are closest to users, so the response is fast and cost-effective, and latency is minimal. This allows for the quick transfer of assets needed for loading internet content, including HTML pages, and static and dynamic content. When the distance data must travel is reduced, users get enhanced performance.

Importance of CDN in Web Performance

A content delivery network (CDN), also known as a delivery networking or application delivery networking, is business-critical for organizations with geographically far-flung staffs or users or both. Every second (and fraction of a second) counts in delivering data when users demand it, and being able to rely on a server that is near a user helps ensure near-real-time data delivery. 

CDNs act as a layer in the internet ecosystem. Content owners such as media companies, social platforms, and e-commerce sites pay CDN operators to cache and deliver their content to their end users. In turn, a CDN operator pays internet service providers (ISPs), carriers, and network operators for hosting its servers in their global data centers.

Traditional web hosting involves containing a website’s data on a single hardware server. While this type of hosting is reliable and secure, it typically is not used alone for internet traffic because of its limited range and functionality. While a CDN does not replace the need for an organization to have a strong, reliable web hosting solution, it complements hosting services by caching content at the network edge. 

This caching causes important backup of data, as well as builds data banks around the world, so it can improve website performance and user accessibility to data, and reduce some of the pain points in traditional web hosting.

Key Concepts of CDN

CDNs can be on-premises data centers or be cloud-based. If your website uses free or shared hosting, a CDN can help you use fewer resources, which are usually limited on such platforms. In case your site experiences traffic spikes, CDNs will also ensure that those surges don’t result in exceeding the resource limit. Here are important functions and terms to help you better understand and get the most out of CDNs.

Origin server: In a connected delivery network, an origin server is the server that stores the original copy of a resource that is being requested by a client. A distributed cloud private link can allow you to configure an origin server over a private link.

Caching: A content delivery network caches content (including images, videos, or webpages) in proxy servers that are located physically closer to end users than origin servers. (A proxy server receives requests from and passes them along to other servers.) Because the servers are closer to the user making the request, a CDN can deliver content more quickly. Caching involves those far-flung servers responding to queries and then storing, or “caching” the information for future use. Caching reduces latency. Cached content remains in the CDN cache as long as users continue to request it.

Edge computing: Edge servers (used with edge clients) are a type of edge device that provides an entry point into a network. CDNs focus on transmitting cached data, while edge computing also supports many other types of computing as well, like live streaming, gaming, and AI.

Points of Presence (PoPs): Points of Presence (PoPs) are interconnected using a multi-terabit, dedicated, and redundant private network for maximum performance. These PoPs are densely peered and connected with multiple Tier1 transit providers to deliver reliable high-quality internet access for applications and consumers. 

Benefits of Using CDN

Any organization that relies on web traffic uptime and availability can benefit from using a CDN. Not only do CDNs work with your primary network to distribute traffic loads, but they distribute it intentionally to the nearest physical point to where the user is located.

  • Improved website load times: By distributing content closer to website visitors, CDNs reduce page loading times, lowering latency, and improving user experience.
  • Reduced bandwidth costs: CDNs optimize data transfer and caching, reducing the amount of data that needs to be transferred from the origin server. This can help lower hosting costs for website owners.
  • Enhanced user experience: This reduced latency and more optimized loading times in turn create better experiences for your users and customers, no matter where they happen to be.
  • Increased content availability and redundancy: CDNs can handle large amounts of traffic and withstand hardware failures better than individual origin servers. This scalability and better load distribution improve website availability and reduce the risk of downtime.
  • Enhanced website security: Some CDNs also provide security features such as mitigating distributed denial of service (DDoS) attacks, as well as improvements to security certificates. These features help protect websites against common malicious attacks.

CDN Implementation

To configure a CDN, you will need your origin server as well as a distributed cloud services account with a reliable cloud computing organization. These are the high-level steps to follow to implement the configuration:

Step 1: Log into the console of your cloud services account and create a new CDN distribution.

Step 2: Configure CDN settings, including metadata, domains, and distribution type.

Step 3: Integrate the origin service by configuring the CDN origin pool.

Step 4: If desired, configure advanced options to control your content delivery operation.

Step 5: Complete creating the distribution.

Step 6: Verify the distribution status. It might take a few minutes for your CDN Distribution to be deployed and to be ready to cache and serve content at Regional Edges.

Step 7: Configure a Secure Sockets Layer (SSL) or a Transport Layer Security (TLS) to secure your network data.

Step 8: Monitor performance for your distributions and adjust as necessary.

Selecting the Right CDN Provider

If you have not implemented a CDN and are looking to do so, it’s important to work with a company that provides the bandwidth and support you need, every step of the way. There are several factors to consider to help you make an informed decision.

  1. Identify your requirements: Determine your specific needs and goals for using a CDN. Consider factors such as geographical coverage, performance, features, pricing, customer support, and scalability.
  2. Research available options: Explore different CDN providers and compare their offerings and reputations in the industry.
  3. Evaluate performance: See how each provider addresses your needs for speed, network connectivity, reliability and uptime, latency, and capacity. Then assess the performance of metrics including DNS response time, connect time, wait time, throughput, and traceroutes. 
  4. Consider security: Ensure that the CDN provider has robust security measures in place to protect your content and data. Look for features such as DDoS protection and secure content delivery.
  5. Review pricing: Compare the pricing models of different CDN providers, including factors like bandwidth usage, data transfer costs, and fees.
  6. Check customer reviews: Read reviews and testimonials from other customers to get insights into their experiences with the CDN providers you are considering.
  7. Seek expert advice: Consult with industry experts or seek guidance from professionals who have experience with CDN providers.

After you’ve done your due diligence, you’ll be able to select the CDN provider that best aligns with your requirements – and your budget.

CDN and Search Engine Optimization (SEO)

Many of the benefits of CDNs discussed previously can also positively affect a website’s and web pages’ search results. It’s important to remember there are no guarantees for any type of effect on search engine result pages (SERP). But optimizing your web experiences in certain ways can potentially help boost your SEO. 

  • Improved page load times: CDNs distribute website content across multiple servers located in different geographic regions. This reduces the physical distance between users and the web host, resulting in faster load times and reduced latency. And that in turn can help positively affect user experience and potentially contribute to better search engine rankings.
  • Improved website availability: CDNs help distribute website traffic across multiple servers, reducing the risk of server overload and downtime. If your website remains reliably accessible to users, that can help it maintain search engine visibility and rankings.
  • Global reach: CDNs have a network of servers located in different regions worldwide. Simply having this global presence can positively affect user experience and search engine rankings, especially for sites with an international audience.
  • Improved mobile experience: CDNs optimize content delivery for mobile devices, ensuring that websites load quickly and efficiently on smartphones and tablets. With the increasing importance of mobile optimization for SEO, using a CDN can help boost your website’s search engine rankings.

Monitoring, Analytics, and Optimizing for CDN

To get the most out of your content delivery network, you need to monitor its operations against your most important KPIs. Then analyze performance and delivery, and lastly, continue to optimize for top performance. 

  • Benchmark the CDN provider: Before you deploy a CDN, get a benchmark of performance from your current website server on its own. Then make sure a CDN will in fact deliver your data more quickly.
  • Monitor the number of trips to the origin server: Keep track of the number of requests made to the origin server. A higher than expected number of trips can mean the CDN is not effectively caching data and using those caches.
  • Choose a CDN available in your regions: Select a CDN service that has servers located in geographic areas where your users are located.
  • Test from different areas: Conduct tests from different geographical locations to ensure consistent performance from everywhere.
  • Load test HTTP/2: To help identify potential bottlenecks and areas of improvement, evaluate the performance of your CDN under heavy load conditions. 
  • Monitor and Optimize Your CDN Over Time: Continuously test your CDN by monitoring files requested from the CDN and your origin server. Regularly update your CDN setup and ensure everything is working well. Here are three methods to help you achieve ongoing optimization:
  1. Cache control headers: Cache control headers are used to specify how long content should be cached by the CDN. By setting appropriate cache control headers, you can control how frequently the CDN fetches content from the origin server, which in turn reduces the load on the origin server.
  2. Content purging and invalidation: Content purging and invalidation allow you to remove or update specific files or content from the CDN cache. This helps to ensure your users are always getting the latest and most relevant information.
  3. Compression and minification: Compression and minification techniques reduce the size of files transferred between the origin server and the CDN servers. Compressing files reduces the amount of data that needs to be transferred, resulting in faster load times, and minification removes unnecessary characters, such as white spaces and comments, from certain files to improve performance.        

Common Challenges with CDN

While content delivery networks can help boost your organization’s digital breadth and reach, CDNs can also can present certain challenges. IT departments should be aware of these potential issues and prevent them, or periodically check operations to make updates and enhancements.

  1. Deployment: Deciding the origin from which the CDN fetches the content and deploying the content in multiple storage systems can be challenging. And that includes initial CDN misconfiguration, which should be corrected as soon as they are discovered.
  2. Regional content discrepancies: You want to deliver seamless, reliable, consistent content to your users, wherever they live. CDNs are intended to deliver just that but sometimes there can be regional content discrepancies. Enable a system for auditing CDN content in different regions, and adjust the performance accordingly.
  3. Versioning and cache-control: Managing updates to static content and deploying new versions can be complex.
  4. Testing: Ensuring that the CDN performs as expected and meets your requirements may require thorough testing.
  5. Content and client security: Protecting your content from unauthorized access or tampering can be a challenge when using a CDN. Deploy a trusted security solution to keep bad actors out of your data and your users’ personal information.
  6. Resilience: Maintaining high availability and resilience in the face of network or infrastructure failures is crucial. After all, organizations deploy CDNs to help increase availability and reliability – so test your system to ensure it is in fact doing that for your organization.

Future Trends in CDN Technology

In recent years, new trends have emerged in helping ensure that CDNs can scale with organizations’ digital growth. Here are some that can help you future-proof your CDN deployment.

Edge computing and CDN integration: The integration of edge computing and CDNs allows organizations to leverage the benefits of both approaches. Edge computing moves actions as close as possible to the source, enabling real-time decision-making and reducing latency. CDNs complement that functionality by ensuring that content is delivered quickly and efficiently by serving it from servers closer to the user.

By combining edge computing and CDN integration, organizations can enhance the user experience, improve application performance, and optimize the delivery of data and content. This is particularly important in scenarios involving the Internet of Things (IoT), where real-time decision-making and low latency are critical.

CDN deployment with HTTP/3 and QUIC protocol: HTTP/3 is a newer internet protocol that is fast growing in popularity and usage. It uses QUIC, a multiplexed transport protocol that gives CDNS lower latency and faster load times. HTTP/3 lower latency and loads much more quickly in real-world use.

AI and machine learning in CDN: The growing availability and use of artificial intelligence (AI) and machine learning (ML) in technology overall presents great opportunities for those using content delivery networks. Here are four benefits we are seeing:

  1. Traffic optimization: AI and ML algorithms analyze network traffic patterns to optimize content delivery by predicting user behavior. 
  2. Intelligent caching: AI and ML models help CDNs intelligently cache content by analyzing user access patterns. 
  3. Anomaly detection: AI and ML algorithms can identify anomalies in network traffic and CDN performance, helping to find and mitigate issues in near-real-time. AI and ML algorithm can also help CDNs detect and mitigate security threats, such as Distributed Denial of Service (DDoS) attacks.
  4. Dynamic content creation with generative AI: AI and ML models can optimize dynamic content delivery by personalizing – and actually creating – content based on user preferences and behavior. This presents an enormous opportunity for content providers – but the upfront costs of investing in creative AI and ML will likely be significant.

How F5 Can Help

At F5, we have deep experience in implementing and protecting content delivery networks (CDNs). We understand that distributing your data, and making it accessible to anyone who needs it, wherever in the world they might live, is a key consideration for your organization. Describe how F5's products and solutions can help implement and protect CDNs.

What’s more, we offer industry-leading integrations of security features to help your organization get the most out of your network, reliably and optimally.