Route 53 and DNS for CloudOps

Route 53 Building Blocks#

Routing Policies#

Health Checks#

Route 53 health checks can monitor public HTTP, HTTPS, or TCP endpoints, CloudWatch alarms, and calculated health checks. For private endpoints, use a CloudWatch alarm as the health check source.

Hands-on: Create a DNS Record for an ALB#

Goal: Point app.example.com to an Application Load Balancer.

1. Create or open a public hosted zone for your domain.
2. Confirm your domain registrar uses the hosted zone name servers.
3. Create an Application Load Balancer or use an existing one.
4. In Route 53, choose Create record.
5. Set record name app, record type A, and Alias enabled.
6. Route traffic to the ALB in its Region.
7. Create the record.
8. Test with:

nslookup app.example.com
curl -I http://app.example.com

Hands-on: Weighted Routing for a Blue/Green Release#

Goal: Send 90% of users to blue and 10% to green.

1. Create two ALBs or two target DNS names: blue for current production and green for the new version.
2. Create an A Alias record named app.example.com.
3. Choose Weighted routing.
4. Set blue weight to 90.
5. Create a second weighted record with the same name and type.
6. Set green weight to 10.
7. Test repeatedly with dig app.example.com.
8. Increase green weight gradually after health and metrics look good.
9. Set green to 100 and blue to 0 when migration is complete.

Hands-on: Failover Routing with Health Checks#

Goal: Route to a secondary Region when the primary endpoint fails.

1. Deploy a primary endpoint in Region A and a secondary endpoint in Region B.
2. Create a Route 53 health check for the primary endpoint using HTTPS and path /health.
3. Create an A Alias record for app.example.com with failover type Primary and associate the health check.
4. Create a second record with the same name and failover type Secondary.
5. Simulate primary failure by returning non-200 on /health.
6. Confirm Route 53 starts returning the secondary target.

Hybrid DNS with Route 53 Resolver#

Use Resolver endpoints when AWS and on-premises DNS must resolve each other:

• Inbound endpoint: on-prem DNS forwards AWS private names into Route 53 Resolver.
• Outbound endpoint: AWS workloads forward selected domains to on-prem DNS.
• Resolver rules: decide which domain suffixes forward where.

Common SOA-C03 Exam Questions#

Q: How do you point a root domain to an ALB? Create an Alias A record at the hosted zone apex.

Q: Which routing policy supports active/passive DR? Failover routing with health checks.

Q: How do private EC2 instances resolve on-premises hostnames? Use Route 53 Resolver outbound endpoints and forwarding rules.

What to Learn Next#

1. AWS VPC Networking - private hosted zones and Resolver endpoints
2. AWS Disaster Recovery for CloudOps - DNS failover patterns
3. EC2 High Availability and Scalability - load-balanced applications behind DNS