Amazon Route 53 health checks are a critical component for building highly available and fault-tolerant architectures on AWS. These health checks monitor the health and performance of your resources, endpoints, and other health checks to ensure traffic is routed only to healthy targets.
There are …Amazon Route 53 health checks are a critical component for building highly available and fault-tolerant architectures on AWS. These health checks monitor the health and performance of your resources, endpoints, and other health checks to ensure traffic is routed only to healthy targets.
There are three types of health checks in Route 53:
1. **Endpoint Health Checks**: Monitor whether an endpoint (IP address or domain name) is healthy by connecting via HTTP, HTTPS, or TCP. You can configure the request interval (10 or 30 seconds), failure threshold, and specify string matching for HTTP/HTTPS checks.
2. **Calculated Health Checks**: Monitor the status of other health checks using Boolean logic (AND, OR, NOT). This allows you to create complex health check hierarchies and determine overall system health based on multiple components.
3. **CloudWatch Alarm Health Checks**: Monitor the state of CloudWatch alarms, enabling you to check metrics like CPU utilization, database connections, or custom application metrics.
Key configuration options include:
- **Health Check Regions**: Route 53 uses health checkers from multiple AWS regions globally
- **Request Interval**: Standard (30 seconds) or Fast (10 seconds)
- **Failure Threshold**: Number of consecutive failures before marking unhealthy (1-10)
- **String Matching**: Verify specific content in response body
Health checks integrate with Route 53 routing policies for automatic failover. When combined with failover routing, traffic automatically shifts to healthy resources when primary endpoints fail. This is essential for active-passive disaster recovery architectures.
For private resources within VPCs, health checks cannot access private endpoints. Instead, create CloudWatch alarms monitoring your resources and use CloudWatch alarm-based health checks.
Best practices include setting appropriate TTL values, using multiple health check regions, and implementing proper alerting through SNS notifications when health status changes.
Route 53 Health Checks - Complete Guide for AWS Solutions Architect Professional
Why Route 53 Health Checks Are Important
Route 53 health checks are a critical component of building highly available and resilient architectures on AWS. They enable automatic failover, ensure traffic is only routed to healthy endpoints, and form the foundation of disaster recovery strategies. For the Solutions Architect Professional exam, understanding health checks is essential as they appear in scenarios involving multi-region deployments, hybrid architectures, and high availability designs.
What Are Route 53 Health Checks?
Route 53 health checks are automated tests that monitor the health and performance of your resources, such as web servers, email servers, or other endpoints. They can monitor:
• Endpoints - IP addresses or domain names • Other health checks - Calculated health checks that combine multiple checks • CloudWatch alarms - State of CloudWatch alarm metrics
How Route 53 Health Checks Work
Endpoint Health Checks: Route 53 sends requests from health checkers in multiple AWS regions worldwide. By default, health checkers from at least 3 regions must report the endpoint as healthy. You can configure:
• Protocol: HTTP, HTTPS, or TCP • Port: The port to check (1-65535) • Path: For HTTP/HTTPS, the path to request • Request interval: 10 seconds (fast) or 30 seconds (standard) • Failure threshold: Number of consecutive failures before marking unhealthy (1-10) • String matching: Search response body for specific string (first 5120 bytes)
Calculated Health Checks: These combine results from multiple health checks using AND, OR, or a threshold (e.g., 2 of 3 must be healthy). Useful for complex failover scenarios.
CloudWatch Alarm Health Checks: Monitor the state of a CloudWatch alarm. Useful for checking internal resources that cannot be reached from the internet, such as private instances or on-premises servers.
Health Check Integration with Routing Policies
Health checks integrate with Route 53 routing policies:
• Failover routing: Primary/secondary failover based on health • Weighted routing: Remove unhealthy endpoints from rotation • Latency-based routing: Route away from unhealthy regions • Geolocation routing: Failover to alternate locations • Multivalue answer: Return only healthy endpoints
Key Configuration Options
• Health checker regions: Customize which regions perform checks • Invert health check status: Mark healthy when check fails • Enable SNI: For HTTPS checks with multiple certificates • Latency graphs: Monitor response times
Exam Tips: Answering Questions on Route 53 Health Checks
Tip 1: When a question mentions monitoring private resources or on-premises servers, think CloudWatch alarm-based health checks. Standard endpoint health checks require public accessibility.
Tip 2: For multi-region active-passive failover scenarios, use failover routing policy with health checks on the primary. The secondary record should have no health check or use Evaluate Target Health.
Tip 3: If a question asks about reducing false positives, look for answers involving adjusting failure thresholds, customizing health checker regions, or using calculated health checks.
Tip 4: String matching health checks are useful when you need to verify application-level health, not just TCP connectivity. Remember the 5120-byte limit for response inspection.
Tip 5: For cost-sensitive scenarios, standard 30-second intervals are cheaper than fast 10-second intervals. Fast checks cost more but provide quicker failover.
Tip 6: When health checks monitor endpoints behind a load balancer, consider using Evaluate Target Health instead of separate health checks to reduce complexity and cost.
Tip 7: Remember that health checkers need to reach your endpoints. Security groups and NACLs must allow traffic from Route 53 health checker IP ranges.
Tip 8: For questions about complex failover logic, calculated health checks allow you to implement sophisticated conditions using multiple child health checks.
Tip 9: Health check status changes trigger CloudWatch metrics and can be used with CloudWatch alarms for notifications via SNS.