Amazon Route 53

Amazon Route 53 is AWS's managed DNS, domain registration, and health-checking service. It combines authoritative DNS hosting with traffic policies that let you route users based on geography, latency, weighted distribution, or the health of your endpoints.

Core Capabilities:

• Domain Registration: Register and transfer domains directly; integrates with Route 53 hosted zones and ACM for TLS.
• Authoritative DNS: Public and private hosted zones with high-availability anycast name servers.
• Alias Records: AWS-specific record type that points to AWS resources (ALB, CloudFront, API Gateway, S3 website) — unlike CNAME, works at the zone apex and incurs no query charges.
• Health Checks: HTTP/HTTPS/TCP probes from multiple regions; can be aggregated into calculated and CloudWatch-metric health checks.

Routing Policies:

• Simple: One record, one target.
• Weighted: Split traffic across multiple endpoints by weight — useful for canary deploys and A/B tests.
• Latency-Based: Route users to the region with lowest network latency.
• Geolocation & Geoproximity: Route by client country/continent, or by distance from AWS regions with a bias factor.
• Failover: Active/passive DNS failover driven by health checks.
• Multi-Value Answer: Up to 8 healthy records returned per query — basic client-side load balancing.
• IP-Based: Route by client IP prefix — useful for ISP- or network-specific targeting.

Private DNS & Hybrid:

• Private Hosted Zones: Resolvable only from associated VPCs — avoids leaking internal names to the public.
• Route 53 Resolver: Hybrid DNS between VPCs and on-premises networks via inbound/outbound endpoints.
• Resolver DNS Firewall: Block or allow outbound DNS queries by domain list — a cheap defense against data exfiltration via DNS.

Route 53 Application Recovery Controller (ARC):

• Readiness Checks continuously verify that standby regions are actually ready to serve.
• Routing Controls are manual on/off switches independent of DNS health checks — used in tightly governed multi-region failover runbooks.
• Zonal Shift moves traffic away from an impaired AZ at the load-balancer level in seconds.