What is a Content Delivery Network (CDN)?

A Content Delivery Network (CDN) is a structure composed of a series of servers that accelerates the distribution of web content. If you want to learn what a CDN is, known as the key to fast websites, and the benefits it offers, let’s dive into the details.

What is a CDN (Content Delivery Network)?

When users try to access websites, they make a request to the server where the website is hosted and receive the content in response. During this process, there is a data flow from the website’s server to the client, i.e., the user. All files on the website, such as text, images, and visuals, are transmitted. Depending on the hosting service, there may be delays and slowdowns in this process.

When websites are slow to load, the use of a CDN comes into play. When a user tries to access a website, they are first directed to the CDN service. Here, they are provided with a cached version of the page they want to access. During the process, servers that are geographically closer to the user are used, allowing the website to be delivered faster.

What are the Benefits of Using a CDN (Content Delivery Network)?

CDN usage provides more than just speed to websites; it also enhances security, reduces costs, and improves search engine performance. Let's explore the benefits of using a content delivery network in more detail.

Improves Loading Times

Speed is the most critical factor when evaluating all web services on the internet. No matter how great a website or application’s features are, if it isn’t fast enough for users, it always falls behind. CDNs allow websites to be delivered faster to users by serving them from locations geographically closer to them.

Reduces Bandwidth Costs

Every file on a website—be it an image, text, or video—creates data traffic when served to users. On websites using a CDN, either the entire site or the data-heavy portion is delivered to users through CDN servers. This prevents the use of the origin server’s bandwidth. Many hosting services offer a monthly limit for bandwidth usage. For high-traffic websites, there is no need to upgrade to a higher hosting solution or pay more for hosting services.

Content delivery services not only optimize bandwidth usage but also ensure the website continues to function smoothly under heavy traffic. Traffic is balanced across CDN servers, allowing users to access the site without interruption.

Minimizes the Impact of Hardware Failures

In addition to handling high traffic, CDN servers located in multiple geographic locations reduce the impact of hardware failures. This ensures users are not affected by any errors that may occur.

Enhances Website Security

Many CDN services come with additional security measures. Features such as DDoS attack prevention and traffic filtering help enhance website security. Suspicious requests from specific locations or IP addresses can easily be blocked. SSL certificates are continually updated to ensure that the communication between visitors and the website remains secure.

Positively Impacts SEO

Search engines aim to provide users with the most accurate and fastest content. While each search engine uses different algorithms and factors, the site that offers the best content most quickly will always rank higher in search results. CDN usage, which significantly improves website load times, is a key part of SEO efforts.

How Does a CDN (Content Delivery Network) Work?

Before we dive into how a CDN works, let’s look at the components that make up this system.

A content delivery network consists of a series of servers distributed across various geographical locations. This network includes edge servers scattered worldwide, which form the CDN service. These servers are connected to the origin server where the website is hosted.

Origin servers are the original source servers where web content is stored. The content hosted on these servers is delivered to users across different locations through the CDN.

Edge servers are CDN servers located at different geographic points worldwide. These servers deliver cached versions of the original content to users nearby. Edge servers are typically located at Points of Presence (PoP), where different networks intersect. PoPs are points where internet service providers and other networks connect.

DNS servers enable the CDN system to function by directing user requests to the nearest CDN server.

To explain how a CDN works with an example: Imagine a website hosted in a data center in Istanbul. If a user located in geographically distant places like the U.S. or Japan wants to visit the site, the data must travel over the internet across this entire distance. Even though this time is calculated in milliseconds, a noticeable delay may occur. With a CDN, users can be served a cached version of the original site from a server located closer to them, reducing the delay.

By using a CDN, the DNS record of the website is directed to the CDN service, so users are first directed to the CDN when they visit the site. This process happens step by step as follows:

• First, the visitor makes a request to access the website. The request reaches the CDN server and is forwarded to the nearest edge server.
• If the requested content is available in the edge server’s cache, it is directly sent to the user.
• If the content is not available on the edge server, the request is forwarded to the origin server by the edge server. The content from the origin server is then delivered to the user.
• The content retrieved from the origin is stored on the edge server for future users, depending on its cache life.
• There are various ways to use a CDN on a website. The entire site can be integrated with a CDN service, or data-heavy content like images and videos can be hosted on a subdomain and delivered through the CDN. In such cases, only the images are served through the CDN, while the rest of the content is fetched from the origin servers.

CDNs offer more than just geographical proximity advantages. To deliver content faster, CDN services apply compression techniques to reduce file sizes. They minimize files by removing unnecessary spaces in source code and optimize image size, quality, and format to reduce the amount of data transmitted and the bandwidth used. Additionally, since CDNs function as storage servers, they are equipped with high-speed storage hardware like SSDs to boost transfer rates

Who Should Use a CDN (Content Delivery Network)?

Content delivery networks can be used by all websites. Considering the contribution of fast websites to search engine optimization, both small and large-scale websites can opt for using a CDN. Moreover, many free and high-quality CDN services are available, allowing sites to use CDN without the need for additional costs. However, for certain types of websites, using a CDN is critically important.

For websites that experience high traffic continuously or periodically and have a large amount of media content, CDN usage is essential. E-commerce sites, streaming platforms, advertising services, media outlets, gaming companies, and social media platforms need CDNs for their operations. E-commerce sites, for instance, must be able to display tens of thousands of products with images to thousands of users simultaneously. Streaming platforms like Netflix, YouTube, and Spotify need to deliver their content quickly and without interruption to millions of users. Likewise, social media platforms, where tens of millions of users share content simultaneously, need to manage the massive amount of traffic. These types of websites, which need to deliver media content to a large audience, must implement CDNs effectively.

Most Popular CDN Services

It’s possible to find CDN services with various features to suit every budget. Before we end our article, we’ve listed three of the most popular CDN services for you.

CloudFlare CDN

CloudFlare, one of the most well-known and widely used CDN services, can be used for free with limited features. With a network that spans over 310 cities in 120 countries, it can reach 95% of the internet-connected population in about 50 milliseconds. Its paid packages offer features like lossless image compression and network prioritization.

Amazon CloudFront

An AWS service, CloudFront speeds up websites with over 600 points of presence (PoP). It has a free plan allowing up to 1TB of data transfer per month and provides additional security features like traffic encryption and access controls.

Fastly CDN

Used by companies like Stripe, GIPHY, and Taboola, Fastly not only boosts speed but also offers customizable features and intelligent video caching. Unfortunately, Fastly does not offer a free plan.

If web technologies excite you and you want to pursue a career in this field, you can take the first step with Techcareer.net’s free Bootcamp courses. You can also find answers to your career-related questions through our community's Discord server or the blog section prepared just for you.