Navigating the Azure Load Balancing Landscape: A Guide to Choosing the Right Option

The term load balancing refers to the distribution of workloads across multiple computing resources. Load balancing aims to optimize resource use, maximize throughput, minimize response time, and avoid overloading any single resource. It can also improve availability by sharing a workload across redundant computing resources.

Azure provides various load-balancing services that you can use to distribute your workloads across multiple computing resources. These resources include Azure Application Gateway, Azure Front Door, Azure Load Balancer, and Azure Traffic Manager.

Service categorizations

Azure load-balancing services can be categorized along two dimensions: global versus regional and HTTP(S) versus non-HTTP(S).

Global vs. regional

• Global: These load-balancing services distribute traffic across regional back-ends, clouds, or hybrid on-premises services. These services route end-user traffic to the closest available back-end. They also react to changes in service reliability or performance to maximize availability and performance. You can think of them as systems that load balance between application stamps, endpoints, or scale-units hosted across different regions/geographies.
• Regional: These load-balancing services distribute traffic within virtual networks across virtual machines (VMs) or zonal and zone-redundant service endpoints within a region. You can think of them as systems that load balance between VMs, containers, or clusters within a region in a virtual network.

HTTP(S) vs. non-HTTP(S)

• HTTP(S): These load-balancing services are Layer 7 load balancers that only accept HTTP(S) traffic. They're intended for web applications or other HTTP(S) endpoints. They include features such as SSL offload, web application firewall, path-based load balancing, and session affinity.
• Non-HTTP(S): These load-balancing services can handle non-HTTP(S) traffic, and we recommend them for non web workloads.

Azure load-balancing services

Here are the main load-balancing services currently available in Azure:

• Azure Front Door is an application delivery network that provides global load balancing and site acceleration service for web applications. It offers Layer 7 capabilities for your application like SSL offload, path-based routing, fast failover, and caching to improve performance and high availability of your applications.
• Traffic Manager is a DNS-based traffic load balancer that enables you to distribute traffic optimally to services across global Azure regions, while providing high availability and responsiveness. Because Traffic Manager is a DNS-based load-balancing service, it load balances only at the domain level. For that reason, it can't fail over as quickly as Azure Front Door, because of common challenges around DNS caching and systems not honoring DNS TTLs.
• Application Gateway provides application delivery controller as a service, offering various Layer 7 load-balancing capabilities. Use it to optimize web farm productivity by offloading CPU-intensive SSL termination to the gateway.
• Load Balancer is a high-performance, ultra-low-latency Layer 4 load-balancing service (inbound and outbound) for all UDP and TCP protocols. It's built to handle millions of requests per second while ensuring your solution is highly available. Load Balancer is zone redundant, ensuring high availability across availability zones. It supports both a regional deployment topology and a cross-region topology.

Decision tree for load balancing in Azure

When you select load-balancing options, consider these factors when you select the Help me choose default tab on the Load balancing page:

• Traffic type: Is it a web (HTTP/HTTPS) application? Is it public facing or a private application?
• Global vs. regional: Do you need to load balance VMs or containers within a virtual network, or load balance scale unit/deployments across regions, or both?
• Availability: What's the service-level agreement?
• Cost: In addition to the cost of the service itself, consider the operations cost for managing a solution built on that service.
• Features and limits: What are the overall limitations of each service?

As we wrap up of Azure's load balancing options, I hope you've gained a clearer understanding of the tools at your disposal for optimizing application performance and ensuring resilience in the cloud. By choosing the right load balancing strategy, you're not just distributing traffic; you're building a foundation for seamless user experiences and robust application architectures.

Embrace the power of load balancing in Azure, and let your applications thrive in a world of seamless connectivity, reliability, and scalability.

Thank you for joining me on this enlightening journey! 🚀🌐

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