Azure Front Door

Application Request Routing (ARR) is an advanced extension for Internet Information Services (IIS) that enables an IIS server to function as a powerful and flexible load balancer. It goes beyond simple traffic distribution by offering content-based routing, allowing administrators to direct requests based on HTTP headers, URL parameters, and server variables. ARR supports various load balancing algorithms and provides features like health monitoring, session persistence, and SSL offloading. Its integration with IIS makes it particularly useful in Windows Server environments, allowing for sophisticated traffic management in web farms and distributed applications. ARR can also act as a reverse proxy, enabling scenarios like caching and request preprocessing.

Amazon Elastic Load Balancing (ELB) is a comprehensive load balancing service provided by AWS that automatically distributes incoming application traffic across multiple targets. ELB offers three types of load balancers: Application Load Balancer (ALB) for HTTP/HTTPS traffic, Network Load Balancer (NLB) for TCP/UDP traffic, and Classic Load Balancer for basic load balancing. ELB can distribute traffic to various AWS resources including EC2 instances, containers, and Lambda functions. It provides features like health checks, SSL/TLS termination, and integration with other AWS services. ELB's ability to automatically scale and its high availability design make it a crucial component for building fault-tolerant and scalable applications in the AWS cloud.

Amazon Application Load Balancer (ALB) is a feature-rich load balancing service that operates at the application layer (Layer 7) of the OSI model. It goes beyond simple traffic distribution by offering content-based routing, which allows routing requests to different target groups based on the content of the request. ALB supports advanced features like host-based and path-based routing, HTTP/2 and WebSocket protocols, and integration with other AWS services like AWS WAF and AWS Certificate Manager. It provides health checks, automatic scaling, and detailed access logs, making it an ideal choice for modern, microservices-based applications deployed in the AWS cloud.