Ch8. CloudFront, Route 53, and Cost Optimization — Completing Your SAA Prep

CloudFront

AWS’s CDN (Content Delivery Network). Caches content at global edge locations to reduce latency.

How it works:

User requests content
Route to nearest edge location
Cache hit: Response from edge immediately
Cache miss: Fetch from origin, cache at edge, respond

Origins:

S3 bucket: Static files, static websites
ALB: Dynamic content
EC2: Custom origin
API Gateway: API response caching

Key features:

HTTPS enforcement
Geo Restriction: block/allow specific countries
OAC (Origin Access Control): Allow only CloudFront to access S3, block direct S3 URLs

Secure S3 static site pattern: Block S3 public access + configure CloudFront OAC. Users access only via CloudFront URL; direct S3 URL returns access denied. Achieves both performance and security.

Route 53

AWS’s DNS service.

Routing policies:

Policy	Description	Use Case
Simple	Single resource	Basic DNS
Weighted	Traffic split by percentage	A/B testing, canary deployments
Latency	Route to lowest-latency region	Global low-latency
Failover	Primary → standby automatic	Disaster recovery
Geolocation	Based on user location	Content localization
Multivalue	Return multiple IPs	Basic load distribution

Health Checks: Route 53 monitors endpoints and automatically routes away from unhealthy ones.

Cost Optimization Strategies

AWS Cost Explorer: Visualize and forecast costs.

Savings Plans vs. Reserved Instances:

Savings Plans: More flexible (applies to EC2, Fargate, Lambda)
Reserved Instances: Optimized for specific instance types

Spot Instance strategy:

Spot Fleets: Buy across multiple instance types and AZs for resilience
Fault-tolerant workloads: batch processing, CI/CD, big data

Storage cost optimization:

S3 Intelligent-Tiering for unpredictable access patterns
EBS snapshot lifecycle policies
Delete unattached EBS volumes

AWS Trusted Advisor: Automated recommendations for cost, security, performance, and fault tolerance.

SAA Exam Core Summary

Security: IAM least privilege, multi-AZ, encryption (at rest + in transit)

Reliability: Multi-AZ, Auto Scaling, ELB, Route 53 failover

Performance: CloudFront CDN, ElastiCache, DynamoDB, Read Replicas

Cost: Spot instances, Savings Plans, S3 lifecycle, serverless

Key Concept Cards

CloudFront OAC ★★★★★ : Block direct S3 access, allow only CloudFront. Standard security pattern for static website hosting.

Route 53 Weighted Routing ★★★★☆ : Split traffic by percentage. Use for canary deployments: 10% → 50% → 100% gradual rollout.

Trusted Advisor ★★★☆☆ : AWS’s automated optimization advisor. Detects cost-saving opportunities and security vulnerabilities.

Practice Quiz

Q1. Korean users should see Korean content; US users should see US content. What Route 53 policy?

Geolocation routing. Configure: Korean IPs → Korean servers, US IPs → US servers. Combined with CloudFront, each region’s content is also cached at nearby edge locations for performance.

Q2. How can you minimize EC2 costs in a development environment?

Use burstable instances (t3.micro, t4g.micro). 2) Auto-stop outside business hours (AWS Instance Scheduler). 3) Use Spot Instances — dev environments tolerate interruption. 4) EC2 Savings Plans for predictable baseline capacity.