AWS Route 53
"DNS and domain registration; health checks and routing"
What is Route 53?
Route 53 is AWS’s DNS service and domain registrar. You manage DNS records (A, CNAME, etc.), health checks, and routing policies (simple, weighted, failover, latency).
Memory hook
"Hosted zone = DNS for a domain; record = name → target; health check = is target up?"
Core concepts
- Hosted zone — container for DNS records for a domain (e.g.
example.com) - Record — maps a name to a value (A, AAAA, CNAME, ALIAS, etc.)
- Health check — Route 53 pings an endpoint; can drive failover
- Routing policy — how Route 53 chooses among multiple records (simple, weighted, failover, latency, geolocation)
Common record types
| Type | Use |
|---|---|
| A | IPv4 address |
| AAAA | IPv6 address |
| CNAME | Alias to another name (e.g. app → ALB) |
| ALIAS | AWS alias (e.g. to S3, CloudFront, ALB); no charge, can use at apex |
| MX | Mail servers |
| TXT | Verification, SPF, etc. |
Typical use cases
- Point domain to ALB/CloudFront — ALIAS or CNAME
- Apex (root) domain — use ALIAS (CNAME not allowed at apex in standard DNS)
- Failover — primary + secondary with health checks
- Weighted / latency — split traffic or route by latency
Health checks
- Route 53 periodically checks an endpoint (HTTP/HTTPS/TCP)
- Unhealthy → can stop returning that record (failover)
- Used for failover routing and monitoring
Interview one-liner
"Route 53 is AWS DNS: hosted zones hold records; you point domains to ALB, CloudFront, or external IPs. Use ALIAS for apex and AWS resources; use health checks and routing policies for failover or traffic splitting."
Cheat sheet
Hosted zone = DNS for domain
A / CNAME / ALIAS = point to server or AWS resource
ALIAS = apex + AWS targets (no CNAME at apex)
Health check = drive failover
Routing = simple, weighted, failover, latency