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Route 53 Public Hosted Zones

A hosted zone is a DNS Database for a domain. RSMUS.com for example. Route 53 is globally resilient. These can be created either with a Route 53 domain registration or standalone with a domain name owned somewhere else Host DNS records A, AAAA, MX, NS, TXT etc Hosted zones become authoritative. To use:

  1. Create a zone
  2. Update the domain's NS records to point to the 4 AWS nameservers to connect to global DNS
  3. Manage your zone via route 53

Internally, the VPC's +2 address points to the Route 53 resolver so that the EC2 instances don't need to query outside AWS in the global DNS namespace.

Route 53 Private Hosted Zones

Private hosted zones are just like the public, but it's only associated AND accessible in the VPC's. You can build out split DNS (public and private for public and internal use with the same zone name. RSM uses split DNS to manage its DNS

To use:

  1. Create a zone
  2. Add records
  3. Access via instances in the VPCs that use the +2 network to resolve to Route 53

Split Horizon DNS​

AWS Documentation Blog Post for further reading

CNAME vs Route 53 Alias

What is the difference between the CNAME and an Route 53 Alias?

Define an A record:

Define a CNAME record:

Cannot have a CNAME from the apex of the domain pointing to anything

Define an ALIAS record within AWS

  • maps a NAME to an AWS resource
  • no charge for an ALIAS record that points to an AWS resource

Simple Routing

Starts with a hosted Zone. Supports one record per name, but one record can have multiple values.

With simple routing, you typically route traffic to a single resource, for example, to a web server for your website.

Health Checks

Health Checks are separate from records but use records to check the health.

  • health checkers are located globally
  • health checks can be performed on common ports, http, https, TCP with StringMatching
  • fire off every 30 seconds. Anything sooner will cost extra.
  • resolve as healthy or unhealthy

Can be one of 3 types of health checks

  • Endpoint
  • CloudWatch alarm
  • Checks of Checks