Amazon Route 53 is AWS's DNS service. Beyond simply translating names into IP addresses, it can choose which answer to return based on health, location, latency or weights. That makes DNS a powerful tool for high availability, gradual rollouts and global applications.
DNS basics in Route 53
- A hosted zone holds the records for a domain. Public zones answer the internet; private zones answer only inside associated VPCs.
- Records have a type (A, AAAA, CNAME, MX, TXT, NS…) and a TTL: how long resolvers cache the answer.
- Alias records are a Route 53 extension that points a name at AWS resources (ALB, CloudFront, S3 website, API Gateway, another record). Unlike CNAMEs, they work at the zone apex (
example.com), cost nothing to query for AWS targets and follow the target's changing IPs automatically.
The routing policies
| Policy | Returns | Use for |
|---|---|---|
| Simple | The record's value(s) | A single resource |
| Weighted | Records in proportion to weights | Canary releases, A/B tests, gradual migrations |
| Latency-based | The Region with the lowest latency for the user | Multi-Region apps |
| Failover | Primary while healthy, otherwise secondary | Active-passive disaster recovery |
| Geolocation | Record for the user's continent, country or state | Localized content, legal restrictions |
| Geoproximity | Nearest resource, with adjustable bias | Shifting traffic between Regions gradually (traffic flow) |
| Multivalue answer | Up to eight healthy records at random | Simple client-side load spreading |
| IP-based | Record based on the client's IP range | Routing specific networks or ISPs |
Weighted routing for safe releases
Create two records with the same name and type, each with a weight. Weights 95 and 5 send roughly 5% of new lookups to the new environment. Increase gradually while watching error rates; set the old weight to 0 to finish. Because resolvers cache answers, keep TTLs low (for example 60 seconds) during migrations.
Latency-based routing
For applications deployed in several Regions, latency records send each user to the Region with the lowest measured network latency from their resolver. Combine with health checks so an unhealthy Region is skipped.
Failover routing and health checks
Failover routing needs a primary and a secondary record. Route 53 returns the primary while its health check passes and the secondary when it fails.
Health checks can monitor:
- An endpoint over HTTP, HTTPS or TCP from checkers in several locations, optionally looking for a string in the response.
- Other health checks (calculated checks combining several with AND/OR logic).
- A CloudWatch alarm, useful for private resources that checkers cannot reach.
For alias records pointing at AWS resources such as an ALB, enable Evaluate target health instead of a separate health check. The secondary can be a static S3 "we'll be right back" page or a warm standby environment in another Region or AZ.
Geolocation vs geoproximity vs latency
- Geolocation is about where the user is (for compliance or language). Always add a default record for unmatched locations.
- Latency is about what is fastest.
- Geoproximity is about distance, with a bias you can tune to expand or shrink a Region's area.
Private hosted zones and hybrid DNS
Private hosted zones give internal names like db.internal.example inside your VPCs. To resolve names between AWS and an on-premises network, use Route 53 Resolver inbound and outbound endpoints with forwarding rules, and protect outbound DNS with Resolver DNS Firewall.
Common pitfalls
- High TTLs that make failover and migrations take hours to reach users.
- Using CNAME at the zone apex (not allowed); use an alias record.
- Health checks blocked by security groups or firewall rules on the endpoint.
- Forgetting that DNS failover only affects new lookups; clients holding connections need application-level retries.
Practice it
Build active-passive failover in Route 53 Failover DR: Primary and Warm Standby. For internal and hybrid DNS, try Private Hosted Zones Across VPCs, Hybrid DNS with Route 53 Resolver and Route 53 Resolver DNS Firewall.
FAQ
Can I register domains in Route 53?
Yes. Route 53 is also a domain registrar, and it creates the hosted zone for you.
Is Route 53 a load balancer?
Not in the traditional sense. It influences which address clients connect to, but it does not see or balance individual connections. Use it with ALBs or NLBs, not instead of them.