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Azure Fundamentals · Lesson

Health Probes and Graceful Degradation

Configure load balancer and Traffic Manager health probes to detect failures quickly, and design circuit-breaker and graceful degradation patterns for your application tier.

Why Health Probes Are Essential

Health probes are the mechanism by which load balancers and traffic managers detect whether a backend instance is capable of serving requests. Without health probes, a load balancer might continue sending traffic to a failed or unresponsive server, causing user-facing errors. Properly configured health probes enable automatic traffic rerouting away from unhealthy instances within seconds of a failure.

Azure Load Balancer Health Probes

Azure Load Balancer supports two types of health probes:

  • TCP probe — checks if the backend can accept a TCP connection on a specified port. Simple but does not verify application logic.
  • HTTP/HTTPS probe — sends a GET request to a specified path and expects a 200 OK response. More accurate because it tests the application endpoint directly.

A backend is marked unhealthy if the probe fails for a configurable number of consecutive attempts.

# Create an HTTP health probe for an Azure Load Balancer:
az network lb probe create \
  --resource-group myRG \
  --lb-name myLoadBalancer \
  --name httpHealthProbe \
  --protocol Http \
  --port 80 \
  --path /health \
  --interval 15 \
  --threshold 2

All lessons in this course

  1. Azure SLAs and Composite SLAs
  2. Availability Sets and Availability Zones
  3. Multi-Region Active-Active Architecture
  4. Health Probes and Graceful Degradation
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