[AWS] Route 53

Route 53 configures and manages domains: domain registration, DNS (Domain Name System) service, and health checking. – DNS uses port 53. That is how the name comes from.

  • Route 53 is commonly used with ELB (Elastic Load Balancer) and CloudFront.
  • Split-View DNS option (Hosted zones) allows maintaining both a private and a public hosted zone with the same domain name.
    • The private hosted zones are allowed with VPCs. Associated VPCs can see the interval version of a website by using the private zone’s A record.
    • A public hosted zone holds the information about how to route the public domain name. The host (www) portion is not included in a public zone’s naming convention.
  • In Route 53, the TTL (Time to Live) is the amount of time that the DNS resolver will cache the record.
  • When creating an A record, you need to specify TTL, a routing policy, and IP values.

Routing Policies

  • Simple routing
    • It uses a single record with multiple IPs within a hosted zone. When queried, all the values are returns in a random order. Simple and default.
    • It evenly spreads requests but no performance control (no LB)
    • Limitations: No granular health checks; No performance control; The alias option can only provide a single AWS resource, not multiple.
  • Weighted routing
    • It controls (splits) the amount of traffic based on the ratio (percentage) of the weight of each record to the total weight of associated records.
    • Weighted routing can be used to test new features of an application by allowing users a gradual introduction to the features.
  • Failover routing: active/passive set up
    • It uses two record sets with the same name (the primary when healthy, the secondary when unhealthy). Route 53 monitors the health of the primary site.
  • Latency-based routing
    • Route53 consults a latency database and resolves the host with the lowest latency.
    • For each record for latency-based routing, you need to specify a region.
    • It is not based on the distance or geolocation. It is based on the network performance.
  • Geolocation routing
    • It serves the traffic based on the geographic region.
    • The requester’s IP is not placed in the specified region, the traffic is routed to the default record.
    • If locations are overlapped, the most specific location is used.
  • Geoproximity routing
    • It must use Route 53 Traffic flow – geographic location of resources.
  • Multivalue Answer routing
    • It may return multiple values, such as IP addresses (simple routing with health checks).

Route 53 Health Checks

  • You can set health checks on individual record sets. A failed record set will be removed from Route 53 until it passes the health check.
  • Types of health checks
    • End Point Checking – agreed way with an agreed frequency (HTTP, HTTPS, TCP – 10 or 30 seconds)
    • Calculated health checks – monitoring various checks and combine them
    • CloudWatch alarms – monitoring CloudWatch alarms from a large range of geographical servers.
  • It provides a summarized report from multiple health checks.
  • Health checks are charged based on the number of checks within the month. (per month base)


  • Route 53 has a default limit of 50 domain names.
  • The limit can be increased by contacting AWS support.

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