I'M Duong

Senior Systems Development Engineer


#white1: What is a CDN? | How does a CDN work?

A content delivery network (CDN) is a collection of geographically dispersed computers that speeds up online content delivery by bringing it closer to consumers. Data centers all around the world employ caching, a method that temporarily saves copies of data, so that you may access internet material more rapidly via a web-enabled device or browser via a server near you. CDNs cache material such as web pages, pictures, and video on proxy servers located near your physical location. This enables you to view a movie, download software, check your bank balance, post on social media, or make transactions without having to wait for the content to load.

Consider a CDN to be similar to an ATM. With a cash machine on almost every corner, getting money is quick and easy. There is no waiting in long bank lines, and ATMs are located in a variety of handy places for easy access.

CDN services were developed to address the issue of network congestion produced by providing rich online content such as graphics and video across the internet — akin to a traffic jam. It just took too long to get material from centrally placed servers to individual users. Text, images, scripts, and media files are increasingly included in CDNs, as are software downloads, documents, portals, ecommerce, live streaming media, on-demand video streaming media, and social networking sites.

CDNs may also provide enhanced protection for websites against malicious actors and security concerns such as distributed denial-of-service (DDoS) assaults.

What is an example of a content delivery network (CDN)?

CDNs supply a substantial part of all online information. Here's an easy example:

If you were in Ho Chi Minh City and wanted to access the website of your favorite retailer in Hongkong, which is hosted on a server in the Hongkong, the request would take a long time to load since it would have to go all the way across the South China Sea. To address this, a CDN would cache the Hongkong website's content at several geographical locations across the world, referred to as "points of presence" (PoPs). These PoPs have their own cache servers and are in charge of providing material near to where you are in Ho Chi Minh City.

Content served from a server nearest to your actual location provides a quicker, more responsive online experience.

How a CDN Works?

A CDN's aim is to minimize latency. Latency is the unpleasant wait you encounter while attempting to view a web page or video stream before it completely loaded on your device. Although it is measured in milliseconds, it might feel like an eternity and may result in a load fault or time-out. Some content delivery networks reduce latency by shortening the physical distance that the material must travel before reaching you. As a result, larger, more widely dispersed CDNs can serve online material more rapidly and reliably by putting it as near to the end user as feasible.

Netflix, Youtube is an excellent example of a CDN.

Assume you're on vacation and want to unwind by viewing the latest Netflix flick - the CDN locates an appropriate server on its network to provide that movie. Typically, the server closest to your current location will be used. The media files will be cached and stored on the content delivery network server for future user requests in the same geographical area. If the requested content is unavailable or out of date, the CDN service will save the newly acquired content to meet future requests.

While website content delivery is a common use for CDNs, it is not their primary function. In actuality, CDNs offer a broad variety of content, such as 4K and HD video, audio streaming, software downloads such as apps, games, and OS upgrades, and much more. A content delivery network has the capacity to disseminate any digital material.

Who makes use of a CDN?

Everyone, in fact. CDNs already provide over 50% of all traffic today. These numbers keep increasing year after year. The point is, if part of your organization is online, there is little reason not to use a CDN, especially since many of them offer their services for free.

However, even as a free service, CDNs aren't for everyone. In particular, if you operate a strictly localized website, with the vast majority of your users located in the same region as your hosting, having a CDN has little benefit. In this scenario, using a CDN can actually degrade your website performance by introducing another non-essential connection point between the visitor and a server already nearby.

However, most websites tend to operate on a larger scale, which makes using CDN a popular choice in the following industries: 

  • Advertising 

  • Media & Entertainment 

  • Online Games 

  • E-commerce 

  • Mobile 

  • Health 

  • Higher education 

  • Government

Why is a CDN necessary? 

CDNs have been the Internet's unseen backbone for more than two decades, supplying online content for commerce, banking, healthcare, and other industries swiftly and at scale.

Without CDNs, which can copy and store information from origin servers and then provide digital material closer to where consumers access the internet, the internet might be slowed to a crawl.

You may not appreciate it, but if you've done nearly everything online, a CDN has most certainly aided in providing you with a quick, dependable, and consistent experience. Here's a simple illustration of how content delivery networks manage traffic behind the scenes to make it happen:

A CDN balances total traffic to provide the best possible online experience to everyone who consumes Internet content. Consider ways to acquire traffic in the actual world. There may be a route that is usually the quickest from point A to point B when there are no other cars, but if the traffic becomes congested, it is better for everyone if the traffic is spread out over several different routes. This might mean that you are sent onto a route that takes a few minutes longer (or a few microseconds, if matched to internet speed), but you are not delayed in traffic on the quicker route. It might also indicate that you are being dispatched on the faster normal route, but without being stuck in traffic, because other cars are being dispatched on longer routes. So it's not a matter of slowing down; rather, it's a matter of balancing the load and making maximum use of available resources.

The point is, without CDNs, we would all be stuck in traffic a lot more often when browsing the web.

What are the advantages of a CDN?

CDNs handle a significant percentage of the world's Internet traffic. They contribute to overcoming the most difficult difficulties of Internet content delivery. Content delivery networks are used by businesses ranging from small and medium-sized content suppliers to huge multinational organizations to provide their consumers with a unified online experience.

Because the Internet was not initially built to accommodate the demands of massive volumes of data, high definition live streaming, flash sales, and big downloads, CDNs were developed to improve Internet performance. all of the interconnected experiences that most of us have in our daily lives today.

CDNs enable the world's businesses and organizations do business online successfully by offering performance, reliability, security, and intelligence solutions.


The difference between a click that provides you quick access to fresh material and a click followed by a seven-second wait as a website loads or a video buffers is called performance. Buffering is the wait period, represented by a recognizable circle indicator on the screen, that happens when an ISP's Internet connection cannot transmit data quickly enough.

How does it function? When a CDN's servers cache requested material, an end user's ISP or mobile phone carrier receives that content by connecting to a server on the CDN's network rather of waiting for his request to travel straight to the origin. The server containing the material you are attempting to view may be located a long distance away from your physical location. If this is the case, a CDN will deliver the material closer to you, increasing speed and performance. Assume Mobile Phone Brand S (MP-S) in Seoul, Korea, introduces a new model for online purchases. S.Fans in Ho Chi Minh City, Hanoi, Danang, and Bangkok all place their orders online. If MP-S does not employ a cloud content management system, each end user must travel to and from Seoul. However, if MP-S employs a CDN and has preloaded its material over the CDN, each user may get fresh content directly from servers in their location, backing up their data for hundreds or thousands of miles round trip.

If the content has not previously been specified, the CDN will utilize its programmed knowledge of the required connections to overcome the problems. Advanced CDNs employ additional technologies to address difficulties with dynamic and non-cacheable content delivery, as well as to select the right type of material to stream to different devices.

All of this implies that when content providers utilize a CDN, they can provide quick, high-quality online experiences to all of their end users, regardless of their location, browser, device, or network from which they connect. Web sites load faster, video buffering times are shorter, and people are more engaged.


Reliability implies that material remains accessible to end users even during periods of high user traffic, when many people access the content at the same time, or when server outages occur in certain areas of the Internet.

Even the most powerful servers are put to the test when traffic approaches millions of requests per second. Without a content delivery network, all of that traffic must be absorbed into the infrastructure of the content provider. This can result in outages and poor user experiences. CDNs' widely spread server infrastructure is intended to minimize these difficulties. With their highly dispersed design and large server platforms, advanced CDNs can absorb tens of Tbps of traffic while also allowing content providers to stay available to user bases.

Let us return to MP-S in Seoul as an example.


As the volume of high-value data and transactions on the Internet grows, so does the number of attackers looking to exploit it. Malicious actors' attacks may be extremely costly to companies. DDoS and online assaults, along with crimes perpetrated by hostile insiders, have proven to be the most expensive.

DDoS assaults and web-based exploits (SQL injection, cross-site scripting, and local or remote file inclusion attacks) are becoming more frequent. These assaults are increasingly being conducted in tandem with a DDoS attack in order to divert attention while causing more significant harm with other vulnerabilities. Both forms of assaults are difficult to differentiate from real traffic, and attack methods vary rapidly over time, necessitating considerable committed security resources to keep on top of strategy attenuation.

With the rising volatility of the Internet security landscape, CDNs must assist in the protection of websites. The most modern content delivery networks of today have made information security a fundamental competence, offering one-of-a-kind cloud-based solutions. CDNs must secure content producers and consumers by mitigating a wide range of threats while ensuring delivery and availability are not jeopardized.


CDN providers collect large volumes of data regarding end-user connectivity, device kinds, and browsing experiences throughout the world as carriers of roughly half of the world's Internet traffic. They may utilize this data to assist their customers by offering vital and actionable insights as well as the intelligence of their user base. Live user monitoring and multimedia analytics to evaluate end-user interaction with web content, as well as cloud security intelligence to track online threats, are examples of these services.

Cloud Computing vs. CDN

The current digital experience has expanded the channels via which organizations deliver their information. CDNs and cloud computing were designed to address the performance and scalability issues posed by the increased demand for web content and applications. How do they vary, though?

Cloud Computing

Cloud computing settings save data on Internet servers rather than on the hard disk of your machine. It may be a simple and dependable medium for webmail, file storage, file sharing, and data backup for end users. also how individuals may quickly access online apps like social media platforms Cloud environments are made up of hundreds of points of presence (PoPs) with centralized servers in regional locations.

For businesses, the cloud provides lower upfront costs as well as the ability to scale application infrastructure as needed, expand into new geographies without investing in costly new infrastructure, and leverage cloud services partners to create digital experiences or the latest business applications.

Although the cloud has numerous advantages, companies frequently encounter unanticipated expenditures when developing or moving applications to the cloud. The dynamic nature of cloud migration initiatives can make maintaining the performance and availability of digital experiences difficult.


A content delivery network (CDN) is a network of servers that delivers material from a "origin" server across the world by caching the content near the point where each end user accesses the Internet via a web-enabled device. The requested material is initially kept on the origin server before being duplicated and stored elsewhere as needed. Latency is decreased by storing content physically near to where a user is and minimizing the distance they must travel. By spreading the load geographically over several servers, this method also decreases stress on the origin servers.

Some individuals refer to content delivery networks as "the limit." The edge is the point at where the physical and digital worlds collide and interact along the network's perimeter. CDNs give greater closeness to end consumers due to their global distribution of thousands of PoPs and unrivaled capacity and scalability.

This means that no matter where you are in the globe, the information you want to access will load faster on your mobile phone, tablet, computer, or other internet-connected device. You may enjoy the same seamless digital experience whether you're watching a home movie on the couch or checking in for a flight to another continent via a content delivery network.

CDN Building Components

Edge Nodes

CDN PoPs (Points of Presence) are strategically positioned data centers that communicate with users in their immediate neighborhood. Their primary purpose is to minimize round trip time by providing material closer to the website's user. Each CDN PoP generally has a large number of CDN Edge Nodes.

CDN Edge Nodes are responsible for storing and delivering cached files. Their main function is to speed up website load times and reduce bandwidth consumption. Each CDN Edge server typically contains multiple storage drives and large amounts of RAM resources.

Cached files are kept on SSD drives and hard disks (SSD and HDD) or in random access memory (RAM) within CDN Edge servers, with the most frequently accessed files housed on the fastest media. RAM is generally utilized to store the items that are accessed the most frequently.

Request Router

This is an important factor of the CDN system since it records the health status of Edge Servers and routes users to the appropriate Edge Node CDNs. The Request Router system distributes users by answering DNS queries or diverting users using the HTTP Redirect method.

The Request Router is considered the heartbeat of the CDN system; its role is basic but critical. The CDN cannot operate without it. And I spent the most of my time at VNG CLOUD researching and developing it when I initially joined.

Analytics Centre

Simply said, the system gathers logs created by CDN Edge Nodes, analyzes them, generates statistics, and saves them back in the central system. Provide consumers with near-real-time visual metrics regarding their website/content.

Next #white: The Rise of CDN

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Duong Nguyen
+84 938-620-379
Ho Chi Minh City, Vietnam