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Amazon Route 53

How DNS Works?​

Route 53​

  • Domain Registrar
  • 100% availability SLA

Records​

  • Each record contains
    • Domain/Subdomain Name
    • Record Type: A/AAAA
    • Value: [IP]
    • Routing Policy
    • TTL

Record Types​

  • A: maps hostname to IPv4
  • AAAA: maps hostname to IPv6
  • CNAME: maps hostname to another hostname
  • NS: Name Servers

Hosted Zones​

  • Container for records on how to route traffic to a domain/subdomain.
  • Public Hosted Zones: route traffic on internet
  • Private Hosted Zones: route traffic within one or more VPC.

Records TTL (Time to Live)​

  • High TTL: Less traffic on Route 53; outdated record.
  • Low TTL: More traffic on Route 53; easy to change records

CNAME vs Alias​

  • CNAME: Points a hostname to another hostname; Only for non root domain.
  • Alias: Points a hostname to an AWS Resource; Cannot set Alias for EC2 DNS name.

Health Checks​

  • HTTP health checks are only for public resources.
  • For Private Hosted Zones, you can create a CloudWatch Metric and associate a CloudWatch Alarm, then create a health check that checks the alarm itself.

Routing Policies​

Simple​

  • Route traffic to a single resource.
  • If multiple values are returned, a random one is chosen.

Weighted​

  • Control the percentage of requests that go to each specific resource.
  • If all the records have the weight of 0, then all the records will be returned equally.

Latency-based​

  • Redirect to the resource that has the least latency close to the user.

Failover​

Geolocation​

  • Based on user's location by continent, country, or by US State.

Geoproximity​

  • Route traffic to your resources based on the geographic location of users and resources.
  • Ability to shift more traffic to resources based on the defined bias.

IP-based Routing​

Multi-Value​

  • Route 53 return multiple values/resources.
  • Can be associated with health checks (return only values for healthy resources)

Hybrid DNS​

  • By default Route 53 resolver answers DNS queries
  • Hybrid DNS: resolving DNS queries between VPC and your networks.