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How Route 53 works

Scalable DNS and health checking. Routing policies: simple, weighted, latency, failover, geo, multi-value. Resolver caching means only a fraction of application requests become billable DNS queries.

DNS is the internet’s address book: it turns names into addresses. Route 53 is AWS’s, but it’s more than a lookup, it’s a traffic director. The same name can resolve to different servers depending on a user’s location, latency, your weighting, or whether the primary is even healthy.

What you will learn

What does DNS actually do, and what does "authoritative" mean?
How do routing policies turn one name into smart traffic steering?
How do health checks give you automatic failover?
Which routing policy fits which goal?

Names to addresses

When something requests app.example.com, DNS resolves it to an IP. Route 53 is the authoritative DNS for your domain, the source of truth that answers "where does this name point?" It also registers domains and hosts your DNS records.

Routing policies: one name, smart answers

A routing policy decides which record to return. Simple returns one. Weighted splits traffic by percentage (great for canary releases). Latency sends users to the lowest-latency region. Geolocation routes by the user’s location. Failover swaps to a backup when the primary is unhealthy.

⚓ Multi-region apps, blue/green and canary rollouts, data-residency routing, and high availability.

Health checks and failover

Route 53 can run health checks against your endpoints. With a failover policy, if the primary fails its check, Route 53 stops handing it out and returns the healthy backup instead, automatic disaster failover at the DNS layer.

Choosing a policy

Match the policy to the goal: latency for performance, geolocation for compliance/localisation, weighted for gradual rollouts, failover for HA, multivalue for simple health-checked round-robin.

Flashcards

What is Route 53’s fundamental function?: Authoritative DNS: resolving your domain’s names to addresses (and registering domains / hosting records).
Which routing policy gradually shifts a percentage of traffic to a new version?: Weighted routing, assign weights to records to split traffic by percentage (canary/blue-green).
How do you send each user to the fastest region automatically?: Latency-based routing returns the region with the lowest latency for that user.
How does Route 53 provide automatic failover, and what slows it?: Health checks + failover policy swap to a healthy backup. Speed is limited by the record TTL (cached answers).
Which policy enforces serving users from specific locations (data residency)?: Geolocation routing, return records based on where the user is.

Sources

Open the SysPad canvas · Official Route 53 documentation