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Hosted Zones

Overview

  • A R53 Hosted Zone is a DNS DB for a domain e.g. myorg.org
  • Globally resilient (multiple DNS servers)
  • Created with domain registration via R53 (also can be created seperately)
  • Host DNS Records (e.g A, AAAA, MX, NS, TXT...)
  • Hosted Zones are what the DNS sytem refrences - Authoritative for a domain e.g. myorg.org

Public Hosted Zone

  • DNS Database (zone file) hosted by R53 (Public Name Servers)
  • Accessible from the public internet
  • as well as from VPCs using R53 Resolver
  • Hosted on 4 R53 Name servers (NS) specific for the zone
  • use NS records to point at these NS (connect to global DNS)
  • Resource Records (RR) created within the Hosted Zone
  • Externally registered domains can point at R53 Public Zone

public-hosted-zone

Private Hosted Zone

  • A Public Hosted zone which is not public

  • Associated with VPCs

    • only accessible in those VPCs
    • using different accounts is supported via CLI/API

  • Split-view (overlapping public and private) for PUBLIC and INTERNAL use with the same one name

private-hosted-zone

Split View Hosted Zones

  • Records in the private hosted zone are not accessible from the public internet
  • Hosted zone associated with VPCs are accessible within the VPCs

split-view-hosted-zone

R53 CNAME vs ALIAS

  • A maps a NAME to an IP address
    • like catagram.ip => 1.2.3.4
  • CNAME maps a NAME to another NAME
    • like www.catagram.io => catagram.io
  • CNAME is invalid for naked/apex
  • Many AWS services uses a DNS name (ELBs)
  • With just CNAME - catagram.io => ELB would be invalid

Alias Records

  • ALIAS records map a NAME to an AWS resoruce
  • Can be used both for naked/apex and normal records
  • For non apex/naked - functions like CNAME
  • For AWS Services -default to picking ALIAS
  • Should be the same Type as what the record is pointing at
  • API Gatewy, Cloudfront, Elastic Beanstalk, ELB, Global Accelerator & s3