Route53 & CloudFront

Route53 is AWS’s DNS service (Domain Name System) — it translates domain names like example.com into IP addresses. CloudFront is a Content Delivery Network (CDN) that delivers content from edge locations worldwide.

Analogy: Route53 is like a phone book for the internet — it tells browsers how to find your website. CloudFront is like a chain of local warehouses — it stores copies of your content closer to users so they get it faster.

sequenceDiagram
    participant User as User Browser
    participant R53 as Route53 DNS
    participant CF as CloudFront CDN
    participant Origin as Origin<br/>(S3 / ELB / EC2)

    User->>R53: What's the IP for www.example.com?
    R53-->>User: CloudFront edge URL

    User->>CF: GET www.example.com/index.html

    alt Cache Hit
        CF-->>User: Cached file ✅ (fast)
    else Cache Miss
        CF->>Origin: Fetch from origin
        Origin-->>CF: index.html
        CF->>CF: Cache at edge
        CF-->>User: index.html ✅ (slower, but cached now)
    end

What Route53 does:

• Registers domain names (or use existing domains)
• Routes users to your AWS resources
• Checks health of your endpoints (health checks)
• Supports failover routing (automatic disaster recovery)

Common record types:

# A record — maps domain to IPv4
aws route53 change-resource-record-sets \
    --hosted-zone-id Z123456 \
    --change-batch '{
        "Changes": [{
            "Action": "CREATE",
            "ResourceRecordSet": {
                "Name": "www.example.com",
                "Type": "A",
                "TTL": 300,
                "ResourceRecords": [{"Value": "203.0.113.10"}]
            }
        }]
    }'

# CNAME — maps domain to another domain
# Alias — maps to AWS resources (free, no TTL cost)

Routing policies:

What CloudFront does:

• Caches content at 300+ edge locations worldwide
• Reduces latency for users globally
• Protects against DDoS attacks (AWS Shield integration)
• Supports static and dynamic content

# Create a CloudFront distribution for an S3 bucket
aws cloudfront create-distribution \
    --origin-domain-name my-bucket.s3.amazonaws.com \
    --default-root-object index.html

CloudFront vs S3 static hosting:

flowchart TB
    subgraph NoCDN["Without CloudFront"]
        User1[User in India] -->|High latency| S3[S3 Bucket<br/>us-east-1]
        User2[User in Brazil] -->|High latency| S3
    end

    subgraph WithCDN["With CloudFront"]
        User3[User in India] -->|Low latency| Edge1[Edge in Mumbai]
        User4[User in Brazil] -->|Low latency| Edge2[Edge in São Paulo]
        Edge1 -->|Origin fetch| S3Origin[S3 Bucket]
        Edge2 -->|Origin fetch| S3Origin
    end

    style NoCDN fill:#ef4444,color:#fff
    style WithCDN fill:#059669,color:#fff

• Route53 = DNS service — maps domain names to your AWS resources
• CloudFront = CDN — caches content at edge locations for faster delivery
• Route53 has routing policies for latency, failover, weighted, and geolocation routing
• CloudFront sits in front of your origin (S3, ELB, EC2) and caches responses
• Together, they make your app fast and reliable globally
• CloudFront also provides DDoS protection via AWS Shield