Amazon Route 53

Amazon Route 53

Amazon Route 53 is a highly available and scalable cloud Domain Name System (DNS) web service. It effectively connects user requests to infrastructure running in AWS (like EC2 instances, Load Balancers, S3 buckets) and can also be used to route users to infrastructure outside of AWS.

Key Concepts

• DNS (Domain Name System): Translates human-readable names (www.google.com) to IP addresses (192.0.2.1).
• Hosted Zone: A container for records, which include information about how to route traffic for a domain.

  • Public Hosted Zone: Internet-facing.
  • Private Hosted Zone: Internal to a VPC.
• Records:

  • A: Hostname to IPv4.
  • AAAA: Hostname to IPv6.
  • CNAME: Hostname to Hostname (Not allowed at Zone Apex/Root e.g., example.com).
  • Alias: AWS Specific. Hostname to AWS Resource (ELB, S3, CloudFront). Allowed at Zone Apex. Free queries.

Routing Policies

1. Simple: Default. Single resource. No health checks.
2. Weighted: Split traffic based on assigned weights (e.g., 80% to V1, 20% to V2). A/B Testing.
3. Latency-based: Route to the region with the lowest latency for the user.
4. Failover: Active-Passive. Route to specific resource if healthy, otherwise backup. (Uses Health Checks).
5. Geolocation: Route based on user's geographic location (Country, Continent). compliance/License content.
6. Geoproximity: Route based on physical distance resources. (Visualized with Traffic Flow).
7. Multivalue Answer: Returns multiple randomly chosen records. Simple Load Balancing.

Features

• Health Checks: Monitor health of endpoints (HTTP/S/TCP). Integrated with CloudWatch.
• Domain Registration: You can buy domain names directly through Route 53.
• Resolver:

  • Inbound: On-prem to AWS.
  • Outbound: AWS to On-prem.

Exam Tips

• Alias vs CNAME: Always choose Alias for AWS resources or Zone Apex.
• High Availability/Disaster Recovery: Think Failover routing policy.
• Global Performance: Think Latency routing policy.
• Local Compliance: Think Geolocation routing policy.
• Route 53 is Global: The service itself is global, not regional.

Common Use Cases

• Mapping domain names to your website/app.
• Implementing Global loads balancing.
• Disaster Recovery strategies (Active-Active or Active-Passive).