Azure CDN vs Azure Front Door: What are the differences?

Azure CDN (Content Delivery Network) and Azure Front Door are both services offered by Microsoft Azure that provide highly scalable and secure content delivery solutions. Here are the key differences between the two.

1. Traffic Routing: Azure CDN primarily focuses on caching and delivering static content like images, CSS, and JavaScript files from edge locations close to the end-user. It uses the nearest edge location to serve the content, reducing latency and optimizing performance. On the other hand, Azure Front Door is designed for dynamic content and supports intelligent routing based on various factors like latency, health probes, and endpoint weighting. It can route traffic to different backend pools and provides flexibility in handling different application scenarios.

2. Protocol Support: Azure CDN supports a wide range of protocols including HTTP, HTTPS, and HTTP/2. It can also be configured to enable WebSocket support. In contrast, Azure Front Door further expands the protocol support by additionally providing WebSockets, Server Name Indication (SNI), and WebSocket routing capabilities. This makes it more suitable for modern web applications that rely on real-time bidirectional communication.

3. Security: Azure CDN provides some security features like content protection, token authentication, and SSL/TLS encryption. However, Azure Front Door offers enhanced security capabilities including Web Application Firewall (WAF) integration and integrated DDoS protection. It acts as a protective layer that can help defend against common web application vulnerabilities and protect the backends from malicious traffic.

4. Global Load Balancing: Azure CDN does not provide native support for global load balancing across different regions. It primarily focuses on content caching and delivery. In contrast, Azure Front Door is specifically designed for global load balancing and enables traffic distribution across multiple regions, allowing for high availability and improved performance by directing users to the nearest healthy backend.

5. Analytics and Monitoring: Azure CDN provides basic analytics and monitoring capabilities to track CDN usage and performance through Azure Monitor and Azure CDN Reports. Azure Front Door, on the other hand, offers more advanced analytics and monitoring features. It integrates with Azure Monitor and Azure Log Analytics, providing detailed insights into traffic patterns, latency, and error rates. This enables better troubleshooting and performance optimization.

6. Traffic Management and Failover: Azure CDN does not provide built-in traffic management and failover capabilities. It relies on DNS for routing. In contrast, Azure Front Door includes advanced traffic management features like weighted routing, session affinity, and URL-based routing. It also supports automatic failover and can intelligently switch between backend pools or endpoints based on health probes and availability.

In summary, Azure CDN focuses on content caching and delivery from edge locations, whereas Azure Front Door provides advanced routing capabilities, global load balancing, enhanced security features, and deeper analytics and monitoring options for dynamic content delivery and application acceleration.