What Is a CDN? A Comprehensive Guide to Content Delivery Networks

The average desktop webpage loading speed is 2.5 seconds, and visitors usually spend less than 15 seconds on your website. Capturing their attention in double-quick time is of the essence. This is where a content delivery network (CDN) comes into the frame.

A CDN is a group of geographically dispersed servers that cache static and dynamic content at the location closest to an end user. This helps improve loading times. Ideally, the quicker your website loads, the more likely the user is to stay on it.

CDNs enhance website reliability, security, and performance and are a vital component of modern internet infrastructure. All major websites, like Amazon, Netflix, and Facebook, use CDNs.

The next time you binge-watch a show on Netflix, tip your hat to CDN technology!

Also referred to as a content distribution network, a CDN is a set of geographically distributed proxy servers and their data centers that cache content like images, videos, and HTML files at edge locations.

This reduces latency and bandwidth costs, improves webpage loading times, ensures better content availability and redundancy, and improves security (more on this soon).

Let’s discuss the core functions, inner workings, key components, and architecture of CDNs.

Core Functions

By now, you should have a working idea of a CDN’s primary function: content distribution.

Content on an origin server is reproduced and distributed to edge servers (aka Points of Presence (PoP)) within a CDN, from which it can be accessed by end users.

Other core functions include dynamic content acceleration (for dynamic content caching), request routing (to discover the most suitable edge locations to meet user requests), and enhanced website security (DDoS protection, for example).

How CDNs Work

To better understand the workings of a CDN, let’s compare it to your local grocery store and origin servers to the nearest poultry farm — no one purchases eggs, for example, directly from a poultry farm.

Visiting the local grocery store is more convenient. These stores “cache” supplies, which you can purchase at will. Let’s explore how caching, content distribution, and optimization work with CDNs.

• Caching: When you request content from a website employing a CDN for the first time, the CDN retrieves it from the origin server, stores a copy at the nearest edge location, and delivers it to you. Subsequent requests are then serviced from the edge location.

• Content distribution: By storing frequently requested static and dynamic content in edge locations, CDNs ensure efficient content distribution, minimize the distance data travels, and reduce latency. The distribution of content closer to website visitors reduces bounce rates and increases engagement as well.

• Optimization: CDNs optimize content delivery by selecting the best route to deliver content to a user, compressing and resizing content (smaller files equate to faster webpage load speeds), removing unnecessary characters from code files, and caching content locally.

It’s clear to see that a website without a CDN is like a sailboat without strong winds.

Key Components

The key components of a CDN include origin servers, edge servers, the caching mechanism, and load balancing. You can think of edge servers as the “backbone” of the entire process. Let’s look into each component in detail.

• Origin servers: While origin servers seem “insignificant” in the grand scheme of things, they’re the source of all the action; All of a website’s data is stored on the origin server initially, before being retrieved by a CDN (when a user requests for it).

• Edge servers: Once a CDN fetches data from an origin server, it’s stored as a cached copy on an edge server closest to the user. These servers are located in numerous data centers globally and play a fascinating role in the modern internet.

• Caching: This data is stored temporarily on edge locations through caching. When a user requests data, the CDN first checks if a cached copy of the data exists on the edge server. If it does, it fetches it, otherwise, it retrieves data from the origin server.

• Load balancing: Load balancing ensures uniformity of user request processing across numerous edge servers. The last thing you need is for a particular edge location to be overwhelmed with requests. This would have the opposite effect of what CDN is supposed to bring to the table.

Now that you understand how the components of a CDN work, let’s study its architecture.

CDN Architecture

Origin servers aren’t really part of CDN architecture (they’re an important component of the content retrieval process) but edge servers are through PoPs.

A PoP is a cluster of edge servers strategically located at high-density traffic locations. It acts like a mini data center and reduces the number of Round-Trip Times (RTTs) data has to undergo when a user requests content.

Every website on the internet should use a CDN service like Cloudflare to speed up content delivery and boost reliability and security.

Luckily, most credible web hosts offer a free CDN subscription with their hosting plans (or offer an economical option as an added service). Listed below are the benefits of CDNs.

Improved Website Performance

By reducing the distance data has to travel to reach an end user, CDNs significantly reduce webpage load times.

Some websites have seen a 50% or more reduction after using a CDN service.

While this is the most obvious performance enhancement measure (through edge server clusters), CDNs also reduce the size of files to increase loading speed and optimize server infrastructure to cater to user requests rapidly — three birds, one stone!

Enhanced Reliability and Availability

CDNs also behave like a GPS navigation system. They find ways around server overload and downtime issues.

If your website is subscribed to a CDN, rest assured your users will receive uninterrupted service.

In the case of a server being overwhelmed (this is unlikely, as CDNs use load balancing techniques) or failing altogether, your CDN service can commence a failover process — this brings a backup server into action.

Global Reach and Scalability

Web hosting providers either have their own data centers or rent server space at data centers around the globe.

It’s nearly impossible to have data centers in every country customers reside in, so CDNs ease the burden on web hosts to deliver instantaneous content.

The global reach and scalability of PoPs make it possible for web hosts to service customers worldwide.

This basically means CDNs allow an American user requesting content from a website (with a data center in the U.S.) to be served just as quickly as a user in Singapore.

Security Enhancements

CDNs are built to withstand DoS attacks and DDoS attacks. In these attacks, miscreants try to overwhelm a website by directing an avalanche of junk network traffic.

DDoS and DoS attacks can cause serious downtime, lost productivity and revenue, and damage brand reputation.

It could also damage SEO rankings (this kind of falls under brand reputation), which may take a long time to recapture.

Luckily, by using a CDN service, you can avoid such attacks, as CDNs can absorb unnatural traffic spikes through their server cluster architecture. CDNs are also effective at avoiding data breaches.

Since the core purpose of a CDN is to accelerate website loading speed, it’s obvious that it has applications in each business sector; I mean, every website owner wants to deliver super-quick content to their users.

Let’s explore how CDNs are particularly useful for eCommerce, media streaming, gaming, and software distribution use cases.

Cloudflare, NitroPack, Sucuri, KeyCDN, and Imperva are some of the best CDN service providers around.

Quite naturally, you may be drawn to the Cloudflare content delivery network, as it’s feature-packed, encompasses data centers in more than 300 cities, and is used by large-scale enterprises like Broadcom, DHL, L’Oreal, and Shopify.

No wonder it’s used by 20.5% of all websites on the internet — roughly 80% of all websites use other CDNs, though. Read on to learn how to choose the right CDN provider for your website.

Factors to Consider

If your budget is on the lower side, you can always opt for a free CDN service like cdnjs.

It’s trusted by more than 12.5% of all websites on the internet and is supported by a strong community that keeps the open-source software running via handsome contributions and donations.

Incidentally, cdnjs is powered by Cloudflare. However, pricing should not be the only factor you consider when choosing a CDN. You should also look out for:

• Performance: The goal of employing a CDN service for your website is to speed it up. When analyzing the performance of a CDN provider, consider metrics like stress tests, location, and Real User Monitoring (RUM) vs. synthetic testing.

• Scalability: As I mentioned earlier, the Cloudflare CDN network spreads across 320 cities. This means it’s more likely to service your website content requests than a CDN service provider limited to select regions only. Make sure to choose a CDN service with PoPs near you.

• Pricing: While a paid CDN service provider isn’t necessarily better than a free one, it’s likely. Assess your budget and select a CDN provider and plan that meets it. A more renowned and widespread CDN tool may be associated with a higher price tag.

• Customer support: Be sure to scour customer reviews on popular product review sites like G2 and TrustPilot and pay special attention to the customer support section. You should opt for a CDN service that’s available 24/7 and offers reliable support through numerous channels (like email, live chat, and phone calls).

BelugaCDN is another fascinating free CDN service. While Cloudflare CDN offers a free plan as well, it’s severely limited — it only supports three page rules and doesn’t include load balancing, mobile optimization, and image resizing!

We recommend the Pro plan, at a minimum, to tackle standard business use cases and the Business plan to use Cloudflare’s full feature set.

Evaluating Providers

We’ve already talked extensively about Cloudflare so let’s explore some of its competitors. If you’re looking for a CDN that’s well, more than a CDN, NitroPack is a solid option.

Alongside content delivery, its optimization services improve the overall performance of your website. We recommend exploring the Growth plan, especially if you anticipate around 200,000 page views per month.

Imperva is another standout CDN service provider. It’s quite similar to Cloudflare and offers a decent free trial period. Some standout features include bandwidth optimization and intelligent caching.

It’s also worth noting websites that use Imperva CDN report a 50% improvement in webpage loading speeds. Impressive.

Tips for Selecting the Right CDN

Your primary consideration when choosing a CDN service provider should be the location of your target audience. If you anticipate most of your user base to reside in the U.S., for example, selecting a CDN with multiple PoP locations in the region makes sense.

We also recommend looking at security features, supported content types, and integration and compatibility with existing infrastructure.

Analyze the CDN service providers employed by local businesses of similar size to your organization, especially if they swear by the same web hosting provider — if it works for them, it may work for you as well!

Case studies (especially in tech) put you in the shoes of another person, give you a fresh perspective, and improve your decision-making skills.

We’ve talked extensively about the benefits of a CDN, and by reviewing the case studies below, you’ll have a better understanding of how CDN services have benefitted these companies.

Here are some successful CDN implementations and the lessons learned from them.

Case Study 1: CacheFly x ON1

CacheFly is a highly adaptable CDN solution that lowers data fees, smoothens traffic spikes, speeds up webpage loading, and offers ultra-low latency and smart image optimization.

White-glove support, granular control, and industry-leading performance are given with CacheFly CDN. ON1 Photo RAW, a premier online photo editing solution, swears by the CDN service provider.

• ON1 rates CacheFly’s customer service as a “positive experience.”
• Plan structure and pricing are crystal clear — CacheFly offers competitive pricing.
• The image optimization tool increased ON1’s website performance.

ON1 believes CacheFly needs to be a little more proactive when launching new technologies, though. The organization didn’t know much about image optimization technology until one of its web developers reached out to customer support.

All in all, ON1 rates CacheFly 8 out of 10 — not bad at all.

Case Study 2: Imperva CDN x NetRefer

Imperva CDN builds failover, content caching, and load balancing into an all-inclusive Web Application and API Protection (WAAP) platform.

The solution offers top-notch webpage loading speed, sturdy performance, and resilience — what more could one ask for? Christian Cutajar, an IT Manager at NetRefer, was full of praise for Imperva’s secure CDN service.

• Imperva CDN’s advanced cache bandwidth capabilities saw a 50% in website performance.
• It also saw a bandwidth consumption reduction of approximately 70%.
• The solution also offers much-needed risk visibility, disruption avoidance, and 24/7 DDoS mitigation.

Imperva CDN offers fantastic support services as well, with comprehensive reporting. One of Imperva’s most impressive features is its 99.999% uptime guarantee — this ensures your customers will enjoy a near disruption-free browsing experience.

Case Study 3: Tata Communications CDN x IBC24

If you’re an up-and-coming broadcast service provider, sit up straight; Tata Communications may have just what you need. The Indian market is a complex one — while many regions are equipped with 5G service, others lack basic 4G or 3G penetration.

IBC24 is a leading new broadcaster in the subcontinent, and they were looking for a CDN service provider that could guarantee the best-in-class service for instantaneous live streaming — Tata Communications delivered.

• Through Tata Communications’ large-scale peering and PoP arrangements with regional ISPs, IBC24 cemented its position as a leading news broadcaster in Tier-2 and Tier-3 cities.
• Proactive monitoring and management features allow IBC24 to stay focused and cover stories that matter.
• Tata Communications’ CDN service increased IBC24’s website performance and support

Kishore Karmakar, VP of IT at IBC24, believes Tata Communications is not just a vendor — it’s “an extension to our company.” No higher praise can be sung of a vendor.

While Tata Communications may not be the best option for other Asian countries, it fares well in North America and Europe, with a CDN edge within 30 ms for any user.

Now that you know what a CDN is, how it works, and its benefits, let’s proceed to the juiciest section of this guide — its practical implementation. Fortunately, it’s not rocket science to implement a CDN service for your website.

Some web hosts make it easy to activate CDN through a control panel like cPanel, while others require you to directly access and manage your subscription through the CDN’s dashboard. Let’s dive straight into it.

Setting up a CDN for a Website or Web Application

Let’s take the example of a free Cloudflare CDN subscription. Many top web hosts include it with their hosting plans and allow you to directly manage Cloudflare settings through a control panel like cPanel or Plesk.

Some, like A2 Hosting, don’t offer the control panel route — you must access the CDN service directly through the Cloudflare dashboard.

Here’s how you can add your newly purchased domain to Cloudflare:

1. Visit Cloudflare’s website and click on “Log In” if you already have a Cloudflare account (through a web host). Click on “Sign Up” if you don’t.

2. Look at the left-hand side of the Cloudflare dashboard. Click on “Websites” followed by “Add a Site.”

3. Enter your domain name and click on “Add Site.”

4. Select the Free plan to continue. Alternatively, you can upgrade to a Pro, Business, or Enterprise plan. Click on “Continue” once you’ve selected a plan.

5. The CDN will scan your website for Domain Name System (DNS) records and import them into your Cloudflare configuration. Click on “Continue” to review your DNS records.

6. At this stage, you must activate your nameservers to point to Cloudflare’s nameservers. Select the My Domains option, click on the domain name you wish to activate for Cloudflare, and access the Manage Nameservers option.

7. You can either access Cloudflare nameservers from “NAMESERVER TEMPLATES” or add them manually. Click on “Save Changes” when done. It may take up to 24 hours for the updates to reflect.

Make sure to activate HTTPS Rewrites through the Settings menu to handle mixed content issues. If all is well, you should see this message reflected on your screen.

For an in-depth understanding of the Cloudflare integration process for your website, we urge you to review this guide. Please refer to the Verify Cloudflare Integration section as well.

Integration With Existing Infrastructure

Selecting a reputable CDN service is the first step toward integrating it with existing infrastructure.

You must ensure it’s compatible with existing content management systems (CMSes), development frameworks, APIs, web servers, and hosting providers.

You should also ensure that your CDN integrates seamlessly with major cloud providers like Azure, Google Cloud, and AWS, which simplifies setup and maintenance.

Four Tips for Optimizing Performance and Monitoring

Simply integrating a proficient CDN service and ensuring its compatibility with existing infrastructure is not enough. You must abide by CDN best practices to optimize performance and monitoring.

1. Static vs. dynamic content: It’s important to optimize both static and dynamic content for efficient delivery. Azure CDN, for example, permits you to optimize the content delivery experience based on your website’s content (images, videos, or live streaming, for example).

You must select an appropriate optimization option to ensure better origin offload and enhanced content delivery performance.

2. Image CDNs: Using image CDNs for faster image loading and a better user experience is important as well.

They automatically adjust image dimensions, save mobile data (we all know how important this is), lead to better Google Search rankings, optimize images for faster webpage loading, and reduce time to first byte (TTFB) by up to 90%.

3. Caching strategies: Some of the most advanced caching techniques employed by CDNs include edge computing, cache-control headers, load-balancing algorithms, and custom caching rules.

Load balancing, in particular, plays an instrumental role in a CDN’s workings (as we’ve explored already). We urge you to explore caching rules to control caching behavior.

4. Bandwidth consumption: Using multiple CDNs is an excellent way to manage bandwidth consumption. While this sounds expensive, you could just use two free CDN services for this.

Using multiple CDNs helps evenly distribute traffic, improving performance, reliability, and redundancy. We also recommend enabling IPv6 connectivity and content compression techniques.

It’s clear that using a CDN will improve the performance of your website. To maximize a CDN service, though, it’s essential you keep these best practices in mind and continuously enhance your knowledge.

Keep an eye on the latest technologies introduced by your CDN provider and try to integrate them as soon as possible; Don’t hesitate to contact customer support if needed.

Troubleshooting Common Issues and Challenges During Implementation

Troubleshooting common CDN implementation issues may frustrate you, but you’d be happy to know the solution to most of them is fairly straightforward. Here are a few of the common challenges you may face and how you can resolve them in a jiffy.

Artificial intelligence (AI) is the new thing. The potential of AI is otherworldly and impossible to predict (ChatGPT is just a drop in the ocean). Watching the evolution of CDN technology and its integration with AI and other emerging technologies like IoT and 5G will be fun.

CDN technology is bound to progress by leaps and bounds in the coming years, and the following insights are merely a drop in the ocean of possibilities.

The web hosting market’s revenue is expected to grow to an astonishing $267.10 billion by 2028 — AWS is leading the way with a market capture of 18.11%.

To stay on top, these web hosting providers must offer leading CDN capabilities, such is its relevance in modern internet architecture; Data centers are spread far and wide and it’s nearly impossible for them alone to deliver content to users instantaneously.

CDNs, through PoP architecture, make this possible. By caching content at edge locations, CDNs speed up the content delivery process to end users. CDNs also optimize content, increase reliability (through failover support), and enhance website security.

If your website doesn’t use a CDN service, now is the right time to purchase one (most web hosts offer a CDN subscription by default). Explore the best CDN providers and integrate one today.