Route 53 failover routing is a critical DNS-based disaster recovery mechanism that ensures high availability for your applications. This routing policy allows you to configure primary and secondary resources, automatically redirecting traffic when your primary endpoint becomes unhealthy.
Failover …Route 53 failover routing is a critical DNS-based disaster recovery mechanism that ensures high availability for your applications. This routing policy allows you to configure primary and secondary resources, automatically redirecting traffic when your primary endpoint becomes unhealthy.
Failover routing works by associating health checks with your DNS records. Route 53 continuously monitors the health of your primary resource through HTTP, HTTPS, or TCP health checks. When the primary endpoint fails health checks, Route 53 automatically routes traffic to your secondary (standby) resource.
There are two main failover configurations:
1. Active-Passive Failover: Your primary resource handles all traffic during normal operations. The secondary resource remains on standby and only receives traffic when the primary fails. This is ideal for disaster recovery scenarios where you want a backup site ready.
2. Active-Active Failover: Both resources can serve traffic, and Route 53 responds with multiple healthy records. This provides load distribution alongside failover capability.
Key components include:
- Health Checks: Monitor endpoint availability using configurable intervals (10 or 30 seconds), failure thresholds, and protocol-specific checks.
- Failover Record Sets: Primary and secondary records pointing to respective resources with identical names but different routing policies.
- Evaluated Target Health: Option to use health status of alias targets like ELB or CloudFront distributions.
Best practices for implementation:
- Set appropriate health check intervals and thresholds to balance responsiveness with false positive prevention
- Configure health check alarms in CloudWatch for visibility
- Test failover scenarios regularly
- Consider TTL values that allow quick propagation during failover events
Failover routing integrates seamlessly with other AWS services like Elastic Load Balancers, S3 static websites, and CloudFront distributions, making it essential for building resilient architectures that maintain business continuity during outages.
Route 53 Failover Routing - Complete Guide
Why Route 53 Failover Routing is Important
Route 53 failover routing is a critical component for building highly available and resilient applications on AWS. It ensures that your applications remain accessible even when primary resources fail, which is essential for meeting business continuity requirements and maintaining service level agreements (SLAs). For the AWS SysOps Administrator Associate exam, understanding failover routing demonstrates your ability to design and implement disaster recovery solutions.
What is Route 53 Failover Routing?
Failover routing is a DNS-based routing policy in Amazon Route 53 that allows you to route traffic to a backup resource when your primary resource becomes unhealthy. It works by configuring two record sets:
• Primary Record: Points to your main resource (e.g., primary web server or load balancer) • Secondary Record: Points to your backup resource (e.g., standby server or static S3 website)
Route 53 monitors the health of your primary resource using health checks and automatically switches DNS responses to the secondary resource when the primary fails.
How Failover Routing Works
1. Health Check Configuration: You create a Route 53 health check that monitors your primary endpoint by sending requests at regular intervals (10 or 30 seconds).
2. Record Set Creation: You create two record sets with the same name but different failover types - one marked as PRIMARY and one as SECONDARY.
3. Health Monitoring: Route 53 continuously monitors the primary endpoint. If the health check fails (based on your configured threshold), the primary is marked unhealthy.
4. Automatic Failover: When the primary is unhealthy, Route 53 begins responding to DNS queries with the secondary resource's IP address or alias.
5. Failback: Once the primary resource recovers and passes health checks, Route 53 automatically routes traffic back to the primary.
Key Configuration Options
• Health Check Intervals: Standard (30 seconds) or Fast (10 seconds - additional cost) • Failure Threshold: Number of consecutive failures before marking unhealthy (1-10) • Health Check Types: HTTP, HTTPS, TCP, HTTP with string matching, or calculated health checks • Evaluate Target Health: Option to use the health of alias targets instead of separate health checks
Common Use Cases
• Active-passive disaster recovery configurations • Failover to static S3 website during outages • Multi-region application deployments • Database failover scenarios with read replicas
Exam Tips: Answering Questions on Route 53 Failover Routing
Tip 1: Remember that failover routing requires health checks on the PRIMARY record. The secondary record's health check is optional but recommended.
Tip 2: Know that DNS TTL (Time to Live) affects how quickly clients recognize failover. Lower TTL values mean faster failover recognition but increased DNS query costs.
Tip 3: Understand that failover routing is for active-passive setups. If a question mentions active-active configurations, consider weighted or latency-based routing instead.
Tip 4: When questions mention cost-effective disaster recovery with minimal infrastructure, think of failover to an S3 static website as the secondary.
Tip 5: Health checks can monitor endpoints, other health checks (calculated), or CloudWatch alarms. Know when each type is appropriate.
Tip 6: If asked about private hosted zones, remember that health checks cannot access private endpoints through VPC. Use CloudWatch alarm-based health checks for private resources.
Tip 7: For questions about RDS failover, remember that Route 53 failover routing is different from RDS Multi-AZ automatic failover. Route 53 handles DNS-level routing, while RDS Multi-AZ handles database-level failover.
Tip 8: Understand that the Evaluate Target Health option for alias records can eliminate the need for separate health checks when pointing to AWS resources like ELBs.