CDN

A content delivery network or content distribution network (CDN) is a geographically distributed network of proxy servers and their data centers.

The goal is to provide high availability and performance (“speed”) by distributing the service spatially relative to end users. CDNs came into existence in the late 1990s as a means for alleviating the performance bottlenecks of the Internet as the Internet was starting to become a mission-critical medium for people and enterprises. Since then, CDNs have grown to serve a large portion of the Internet content today, including web objects (text, graphics and scripts), downloadable objects (media files, software, documents), applications (e-commerce, portals), live streaming media, on-demand streaming media, and social media sites.

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

CDN is an umbrella term spanning different types of content delivery services: video streaming, software downloads, web and mobile content acceleration, licensed/managed CDN, transparent caching, and services to measure CDN performance, load balancing, Multi CDN switching and analytics and cloud intelligence. CDN vendors may cross over into other industries like security, DDoS protection and web application firewalls (WAF), and WAN optimization.

How Does CDN (Content Delivery Network) Work ?

A Content Delivery Network (CDN) is a system of distributed servers strategically located across various regions to deliver web content to users more quickly and efficiently. The primary goal of a CDN is to reduce latency, which is the delay that occurs when data travels between a server and a user.

CDN nodes are usually deployed in multiple locations, often over multiple Internet backbones. Benefits include reducing bandwidth costs, improving page load times, and increasing the global availability of content. The number of nodes and servers making up a CDN varies, depending on the architecture, some reaching thousands of nodes with tens of thousands of servers on many remote points of presence (PoPs). Others build a global network and have a small number of geographical PoPs.

These Internet exchange points (IXPs) are the primary locations where different Internet providers connect in order to provide each other access to traffic originating on their different networks. By having a connection to these high speed and highly interconnected locations, a CDN provider is able to reduce costs and transit times in high speed data delivery.

Beyond placement of servers in IXPs, a CDN makes a number of optimizations on standard client/server data transfers. CDNs place Data Centers at strategic locations across the globe, enhance security, and are designed to survive various types of failures and Internet congestion.

Requests for content are typically algorithmically directed to nodes that are optimal in some way. When optimizing for performance, locations that are best for serving content to the user may be chosen. This may be measured by choosing locations that are the fewest hops, the lowest number of network seconds away from the requesting client, or the highest availability in terms of server performance (both current and historical), to optimize delivery across local networks.

When optimizing for cost, locations that are the least expensive may be chosen instead. In an optimal scenario, these two goals tend to align, as edge servers that are close to the end user at the edge of the network may have an advantage in performance or cost.

Most CDN providers will provide their services over a varying, defined, set of PoPs, depending on the coverage desired, such as United States, International or Global, Asia-Pacific, etc. These sets of PoPs can be called “edges”, “edge nodes”, “edge servers”, or “edge networks” as they would be the closest edge of CDN assets to the end user.

By bringing content closer to users, a CDN enhances the speed, reliability, and security of websites and applications.

Here’s a step-by-step overview of how a CDN delivers content:

1. Caching Content
   • CDNs cache (store) copies of static content, like images, videos, CSS, JavaScript files, and HTML pages, across multiple servers called edge servers or PoPs (Points of Presence) around the globe.
   • When a user requests content, the CDN serves cached content from the nearest edge server, rather than fetching it from the original server (known as the origin server), which may be located far from the user.
2. Locating the Nearest Edge Server
   • CDNs use a process called Geo-DNS (Geographic Domain Name System) to route users to the closest CDN edge server based on their geographic location.
   • This process is automatic, and it reduces the distance data needs to travel, minimizing the time required for each request.
3. Fetching Uncached Content
   • If the requested content isn’t available on the nearest edge server, the CDN will retrieve it from the origin server, cache it on the edge server, and then deliver it to the user.
   • The next time a user near that location requests the same content, it will be served directly from the cache, improving speed and reducing load on the origin server.
4. Load Balancing
   • CDNs often use load balancing to distribute user requests across multiple servers to prevent any single server from becoming overwhelmed. This improves reliability and ensures consistent performance.
5. Content Expiration and Refreshing
   • Cached content on a CDN edge server has an expiration time (known as Time to Live or TTL). When the TTL expires, the edge server refreshes the content by fetching an updated version from the origin server.
   • Website administrators can control how long content stays cached and set rules for when content should be refreshed.
6. Compression and Optimization
   • CDNs can optimize content by compressing images, minifying JavaScript and CSS files, and reducing the overall size of the data that needs to be transferred. This helps further improve load times for users.
7. Secure Content Delivery
   • Many CDNs offer built-in security features, like SSL/TLS encryption, to protect data in transit. CDNs can also help prevent attacks, such as Distributed Denial of Service (DDoS), by absorbing malicious traffic and filtering out unwanted requests.

Benefits of Using a CDN

1. Improved Load Times
   • By serving content from the nearest edge server, CDNs drastically reduce the time it takes for a page to load, which enhances user experience and can increase engagement.
2. Reduced Bandwidth Costs
   • CDNs reduce the amount of data that needs to be served from the origin server by caching content, which can lower hosting costs, especially for websites with high traffic.
3. Enhanced Reliability and Availability
   • With multiple edge servers distributed worldwide, CDNs offer redundancy. If one server goes down, another can take over, ensuring high availability and consistent uptime.
4. Better Handling of Traffic Spikes and Reduce Bandwidth Costs
   
   • CDNs help manage large volumes of traffic by distributing requests across multiple servers. This prevents the origin server from becoming overwhelmed during traffic spikes.Every time an origin server responds to a request, bandwidth is consumed.
5. Security
   • CDNs offer enhanced security with features like DDoS protection, SSL encryption, and Web Application Firewalls (WAFs), helping protect websites and applications from various threats.Information security is an integral part of a CDN. a CDN can keep a site secured with fresh TLS/SSL certificates which will ensure a high standard of authentication, encryption, and integrity. Investigate the security concerns surrounding CDNs, and explore what can be done to securely deliver content.

Use Cases for a CDN

1. Website and E-commerce Platforms
   • Faster page load times are crucial for user experience and conversion rates, making CDNs ideal for e-commerce sites and content-rich websites.
2. Media and Video Streaming
   • CDNs are essential for video-on-demand platforms, live streaming, and image-heavy websites because they reduce latency and buffer times.
3. Global Applications
   • Applications with a global user base can ensure consistent performance across regions by using a CDN to serve localized content quickly.
4. Mobile Content Delivery
   • CDNs optimize content delivery for mobile users by compressing and caching data for devices that may have lower network speeds.

How Does a CDN Keep a Website Always Online?

Uptime is a critical component for anyone with an Internet property. Hardware failures and spikes in traffic, as a result of either malicious attacks or just a boost in popularity, have the potential to bring down a web server and prevent users from accessing a site or service. A well-rounded CDN has several features that will minimize downtime:

• Load balancing distributes network traffic evenly across several servers, making it easier to scale rapid boosts in traffic.
• Intelligent failover provides uninterrupted service even if one or more of the CDN servers go offline due to hardware malfunction; the failover can redistribute the traffic to the other operational servers.
• In the event that an entire data center is having technical issues, Anycast routing transfers the traffic to another available data center, ensuring that no users lose access to the website.

How Many Types of Content Networking Techniques ?

There are several types of content networking techniques, each designed to optimize the delivery of digital content by different methods.

These techniques vary based on how they handle caching, request routing, and overall content delivery. Here are some of the most common types:

1. Content Delivery Networks (CDNs)

• Definition: CDNs are distributed networks of servers that cache and deliver content to users from locations close to them.
• Function: CDNs reduce latency and improve load times by serving cached content from nearby edge servers.
• Use Cases: Popular for websites, video streaming, software downloads, and global applications.
• Examples: Akamai, Cloudflare, Amazon CloudFront, Microsoft Azure CDN.

2. Application Delivery Networks (ADNs)

• Definition: ADNs are similar to CDNs but focus on delivering dynamic, application-level content.
• Function: ADNs optimize application performance by distributing applications across multiple locations and using techniques like load balancing, compression, and application-layer security.
• Use Cases: Useful for applications that require fast access to dynamic content, such as e-commerce sites and financial platforms.

3. Peer-to-Peer (P2P) Content Distribution

• Definition: P2P networks use a decentralized approach, where users (peers) share resources among each other to distribute content.
• Function: Content is broken into parts, and each peer downloads parts from other peers, reducing load on central servers.
• Use Cases: Ideal for large file transfers and streaming in scenarios where server bandwidth is a limiting factor, like in file sharing or large game updates.
• Examples: BitTorrent, IPFS (InterPlanetary File System).

4. Dynamic Content Acceleration (DCA)

• Definition: DCA focuses on accelerating the delivery of dynamic, non-cacheable content that cannot be stored on edge servers.
• Function: Uses techniques like TCP optimization, route optimization, and protocol tuning to improve delivery speed of dynamic content.
• Use Cases: Useful for real-time applications and dynamic websites with personalized content, such as online banking and social media.

5. Edge Computing and Edge Caching

• Definition: Edge computing extends computation and data storage closer to the data source (the “edge” of the network).
• Function: By processing data at the edge, it reduces latency and network congestion, allowing faster response times.
• Use Cases: IoT applications, AR/VR applications, autonomous vehicles, and scenarios requiring real-time data processing.

6. Multicast Content Distribution

• Definition: A network technique where content is delivered to multiple users simultaneously using a single stream of data.
• Function: Data is sent once and distributed to multiple recipients without duplicating the content, making it bandwidth-efficient.
• Use Cases: Used in live video streaming, IPTV, and online radio where the same content needs to be broadcast to many users.

7. Web Caching and Proxy Caching

• Definition: This involves storing copies of frequently accessed web content in proxy servers closer to users.
• Function: Web caches (proxy servers) temporarily store web resources and serve them to users without repeatedly accessing the origin server, reducing load times and saving bandwidth.
• Use Cases: Common for large networks like ISPs and enterprise networks, where caching popular sites can improve access speed and reduce bandwidth usage.

8. Global Load Balancing

• Definition: Global load balancing is a technique that distributes traffic across multiple data centers or servers based on user location, server availability, and load.
• Function: Balances the load among multiple servers in various geographic locations to ensure high availability and low latency.
• Use Cases: Useful for applications requiring high availability and redundancy, such as large-scale e-commerce sites and global applications.

TOP 20 CDN Service Provider

Here’s a list of the top 20 Content Delivery Network (CDN) providers, known for their speed, security, scalability, and unique feature sets. These CDNs are popular for delivering web content, streaming media, software, and more across the globe.

Top 20 CDN Providers

1. Akamai
   • One of the largest and oldest CDNs, known for its extensive global network, security features, and advanced caching.
2. Cloudflare
   • Offers CDN, security (DDoS protection, WAF), and performance optimization. Known for an easy-to-use interface and free plan.
3. Amazon CloudFront
   • AWS’s CDN integrates with other AWS services, providing scalability, security, and customizability.
4. Microsoft Azure CDN
   • Part of Azure’s cloud ecosystem, offering scalable, secure content delivery optimized for Microsoft services.
5. Google Cloud CDN
   • Integrated with Google’s cloud services, it offers fast global delivery, particularly beneficial for Google Cloud users.
6. Fastly
   • Known for real-time content delivery, instant purging, and powerful edge computing capabilities.
7. KeyCDN
   • A budget-friendly CDN with global coverage, supporting HTTP/2 and TLS 1.3 for faster load times and security.
8. StackPath
   • Offers both CDN and edge computing solutions, focusing on security and ease of integration for developers.
9. CDN77
   • Known for high-performance, high-speed delivery, particularly in Europe. Offers support for live streaming and on-demand video.
10. Limelight Networks
    • Specializes in video and online gaming content delivery, with a focus on low latency and high availability.
11. CacheFly
    • One of the fastest CDNs, known for reliability and performance, especially in video and large file delivery.
12. BunnyCDN
    • A cost-effective CDN with a user-friendly interface, ideal for small to mid-sized websites and media.
13. SUCURI
    • A CDN with a strong focus on website security, offering DDoS protection and a web application firewall.
14. Alibaba Cloud CDN
    • A leading CDN in Asia, providing robust delivery solutions with deep integration into Alibaba’s cloud ecosystem.
15. Verizon Media (Edgecast)
    • Strong in live streaming and video delivery, with a large network footprint and enterprise-level features.
16. Incapsula (Imperva)
    • Known for its security features, including DDoS protection and bot mitigation, alongside its CDN services.
17. Rackspace CDN
    • Powered by Akamai, this CDN offers a simple setup for Rackspace customers, focusing on small to mid-sized businesses.
18. Quantil
    • Focuses on content delivery in China and Asia-Pacific, providing services for video streaming, gaming, and e-commerce.
19. Tencent Cloud CDN
    • Known for content delivery within China and Asia-Pacific regions, it provides reliable delivery for Tencent’s own services.
20. ArvanCloud
    • A newer CDN offering advanced features like edge computing, streaming support, and security-focused services.

• How to Choose the Right CDN Provider ?