Route 53

Solution Architect Associate

Developer Associate

Security Specialty

  • ELBs don’t have pre-defined IPV4 addresses, you always use an alias record to point to the DNS name
  • Alias records can be used for naked domain names, CNAMES cannot
  • Given the choice, always use an alias record over a CNAME
  • R53 is a Global Service (likely on test)
  • Understand the types of DNS records
  • You can only manage 50 domain names per account by default, but you can contact AWS to raise the limit (may be on test)

Routing Policies

Simple Routing

  • If you choose this, you can only have one record with multiple IP addresses. If you specify multiple values in a record, R53 will return all values to the user in a random order.

Weighted Routed

  • You need to one record for each set of IPs you want to weight, typically just 1 per record.
  • Allows you to specify a percentage of all requests to R53 get distributed to the different records you add.
  • Weight is defined in percentages as whole numbers, no %s and no decimals (i.e. 25 not 0.25)
    • The numbers are all added up, so if you specify one at 25 and one at 75 you’d get a 1-4 ratio. But if you set one at 25 and one at 100, you’d have a 1-5 ratio.

Latency Based Routing

  • Allows you to route traffic based upon lowest latency for your end user
  • You create a record set for your EC2 or ELB resource in each region that hosts your assets

Failover Routing

  • Used when you want to create an active/passive setup
  • R53 will monitor the health of the primary site using a health check

Geolocation Routing

  • Lets you route traffic will be sent based upon a geographic location of your user (i.e. where the DNS queries originate)
  • For example, you may want to route users to properly localized websites that display offers, prices, etc. based upon location (USD for US, JPY for Japan, etc.)

Geoproximity Routing

  • Uses a combination of geographic location, latency and availability to route traffic to cloud or on-premises endpoints
  • Highly complex routing is allowed
  • Only available if you’ve created a traffic flow routing policy
  • You can optionally choose to route ore traffic or less to a given resource by specifying a value known as a bias
    • A bias expands or shrinks the geographic region from which traffic routed to a resource

Multi-Value Answer Routing

  • If you want to route traffic approximately randomly to multiple resources, you can create a multi-value answer record for each resource
  • Create one multi value answer record for each IP, optionally can associate a health check as well
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