Intro

• Global Service
• AWS managed Authoritative DNS (customer can update the DNS records and have full control over the DNS)
• Also a Domain Registrar (for registering domain names)
• Only AWS service which provides 100% availability SLA
• Affected by client's DNS caching (not suitable for Blue-Green Deployment if the client caches DNS queries)

<aside> 💡

It is recommended to use DNS names or URLs instead of IPs wherever possible

</aside>

Hosted Zone

• A container for DNS records that define how to route traffic to a domain and its subdomains.
• Hosted zone is queried to get the IP address from the hostname
• Two types:
  • Public Hosted Zone
    • resolves public domain names
    • can be queried by anyone on the internet
  • Private Hosted Zone
    • resolves private domain names
    • can only be queried from within the VPC

Record Types

• A - maps a hostname to IPv4
• AAAA - maps a hostname to IPv6
• CNAME - maps a hostname to another hostname
  • The target is a domain name which must have an A or AAAA record
  • Cannot point to root domains (Zone Apex) Ex: you can’t create a CNAME record for example.com, but you can create for something.example.com
• NS (Name Servers) - controls how traffic is routed for a domain
• Alias - maps a hostname to an AWS resource
  • AWS proprietary
  • Can point to root (zone apex) and non-root domains
  • Alias Record is of type A or AAAA (IPv4 / IPv6)
  • Targets can be
    • Elastic Load Balancers
    • CloudFront Distributions
    • API Gateway
    • Elastic Beanstalk environments
    • S3 Websites
    • VPC Interface Endpoints
    • Global Accelerator
    • Route 53 record in the same hosted zone
  • Target cannot be EC2

Routing Policies