5.1.2.4. Design for Azure DNS and Azure Traffic Manager

💡 First Principle: An intelligent, global traffic routing system is essential for building high-performing, resilient, and globally available applications by directing user requests to the optimal endpoint based on health, latency, or geography.

Scenario: You are designing a global web application with active deployments in East US and West Europe Azure Regions. You need to route users to the geographically closest region for optimal performance. In case of a regional outage in one region, traffic should automatically failover to the other region.

Azure DNS is a managed service for hosting DNS domains, and Azure Traffic Manager is a DNS-based traffic load balancer.

Key Design Considerations:

• Azure DNS:
  • Purpose: Hosts your DNS domains and provides name resolution using Microsoft's global DNS infrastructure.
  • Use Cases: Public DNS for web applications, private DNS for VNet resources (Azure DNS Private Zones).
• Azure Traffic Manager:
  • Purpose: A DNS-based traffic load balancer that distributes traffic globally across your application endpoints.
  • Routing Methods: Choose from Priority (failover), Weighted, Performance (latency-based), Geographic, MultiValue, or Subnet routing.
  • Endpoint Monitoring: Continuously monitors endpoint health and automatically routes traffic away from unhealthy endpoints.
  • Use Cases: Global load balancing, disaster recovery (failover to secondary Region), and optimizing user experience.
• Integration: Traffic Manager uses Azure DNS to resolve the appropriate endpoint based on the chosen routing method.

⚠️ Common Pitfall: Confusing Azure Traffic Manager with Azure Load Balancer. Traffic Manager is a DNS-based, global service that directs clients to an endpoint. Load Balancer is a regional service that distributes traffic within a region to specific VMs or services.

Key Trade-Offs:

• DNS-based (Traffic Manager) vs. Anycast-based (Azure Front Door): Traffic Manager provides DNS-level routing. For more advanced features like SSL offloading, WAF, and Anycast-based routing over the Microsoft backbone, Azure Front Door is the more powerful (and more expensive) option.

Reflection Question: How does designing for Azure DNS (for hosting the domain) and Azure Traffic Manager (with a Performance routing method for latency and endpoint monitoring) fundamentally enhance the global availability and performance of your applications by intelligently routing user requests to the optimal available endpoint?