Today’s focus is on building resilient architectures that can withstand failures and recover quickly. These concepts are critical for real-world enterprise deployments and frequently tested in the AWS Solutions Architect Associate exam.
🎯 Study Objectives
- Understand Multi-AZ and Multi-Region architectures
- Learn about Route 53 failover routing, Elastic Load Balancing, and Auto Scaling
- Explore RTO (Recovery Time Objective) and RPO (Recovery Point Objective)
- Compare Backup & Restore, Pilot Light, Warm Standby, and Multi-Site Active/Active strategies
📘 Key Topics & Services
✅ High Availability
- Elastic Load Balancer (ELB): Distributes traffic across healthy targets in multiple AZs
- Auto Scaling Groups (ASG): Automatically adjusts capacity based on demand
- Multi-AZ RDS: Synchronous replication for failover protection
✅ Disaster Recovery Models
| Strategy | RTO | RPO | Cost | Notes |
|---|---|---|---|---|
| Backup & Restore | Hours | Hours | Low | Simple, cost-effective |
| Pilot Light | Minutes | Hours | Medium | Core services always running |
| Warm Standby | Seconds | Minutes | Higher | Scaled-down version always on |
| Multi-Site Active | Real-time | Real-time | Highest | Full capacity in multiple regions |
✅ DNS Failover
- Route 53 Health Checks + Failover Routing Policy
- Use with S3 static websites, EC2, or ELB endpoints
🧠 Exam Tips
- Know how Auto Scaling and ELB work together for fault tolerance
- Understand Route 53 failover and latency-based routing
- Be able to choose the right DR strategy based on RTO/RPO requirements
- Expect scenario-based questions comparing HA vs DR trade-offs
🧪 Hands-On Labs
- Create an Auto Scaling Group with ELB across two AZs
- Configure Route 53 failover using health checks
- Simulate an EC2 failure and observe recovery behavior
📎 Resources
- AWS Well-Architected Framework – Reliability Pillar
- Disaster Recovery Whitepaper
- Tutorials from AWS Skill Builder or free-tier labs
✅ Summary
Day 5 reinforces the importance of designing for failure. Whether you’re deploying a critical enterprise app or a training environment, understanding HA and DR principles ensures your architecture is resilient, scalable, and exam-ready.