Learning AWS - DVA - Day 15: Route 53 Routing Policies

Overview

• Define how Route 53 responds to DNS queries

• Don't get confused by the word "Routing"

  • It's not the same as Load Balancer routing which routes the traffic
  • DNS does not route any traffic, it only responds to the DNS queries

• Route 53 supports the following Routing Policies

  • Simple
  • Weighted
  • Failover
  • Latency based
  • Geolocation
  • IP-based
  • Multi-Value Answer
  • Geoproximity (using Route 53 Traffic Flow feature)

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Routing Policies - Simple

• Typically, route traffic to a single resource

• Can specify multiple values in the same record

• If multiple value are returned, a random one is chosen by the client

• When Alias enabled, specfy only one AWS resource

• Can't be associated with Health Checks

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Routing Policies - Weighted

• Control the % of the requests that go to each specific resource

• Assign each record a relative weight:
  traffic(%) = weight of the records / sum of all the weight

• Weights don't need to sum up to 100

• DNS records must have the same name and type

• Can be associated with Health Checks

• Use cases: load balancing between regions, testing new application versions, ...

• Assign a weight of 0 to a record to stop sending traffic to a resource

• If all records have weight of 0, then all records will be returned equally

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Routing Policies - Latency-based

• Redirect to the resource that has the least latency close to us

• Super helpful when latency for users is a priority

• Latency is based on traffic between users and AWS Regions

• Germany users may be directed to the US (if that is the lowest latency)

• Can be associated with Health Checks (has a failover capability)

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Routing Policies - Failover (Active - Passive)

• You designate a primary resource and a secondary (or failover) resource. The primary resource is the one that Route 53 will route traffic to under normal conditions

• Route 53 performs health checks on the primary resource to determince its availability

• If the primary resource becomes unhealthy, Route 53 will redirect traffic to the secondary resource without manual intervention

• Use cases: high vailability dns, desaster recovery

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Routing Policies - Geolocation

• Different from Latency-based

• This routing is based on user location

• Specify location by Continent, Contry or by US State (if there is overlapping, most precise location selected)

• Should create a "Default" record (in case there is no match on location)

• Use cases: website localization, restrict content distribution, load balancing, ...

• Can be associated with Health Checks

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Routing Policies - 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

• To change the size of the geographic region, specify bias values:

  • To expand (1 to 99) - more traffic to the resource
  • To shrink (-1 to -99) - less traffic to the resource

• Resources can be:

  • AWS resources (specify AWS Region)
  • Non-AWS resources (specify Latitude and Longitude)

• You must use Route 53 Traffic Flow (advanced) to use this feature

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Routing Policies - IP-basd Routing

• Routing is based on client's IP addresses

• You provide a list of CIDRs for your clients and the corresponding endpoints/locations (user-IP-to-endpoint mappings)

• Use cases: Optimize performance, reduce network costs, ...

• Example: route end users from a particular ISP to a specific endpoint

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Routing Policies - Multi-Value

• Use when routing traffic to multiple resources

• Route 53 return multiple values/resources

• Can be associated with Health Checks (return only values for healthy resources)

• Up to 8 healthy records are returned for each Multi-Value query

• Multi-Value is not a substitue for having an ELB

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Domain Registrar vs DNS Service

• You buy or register your domain name with a Domain Registrar typically by paying annual charges (e.g., GoDaddy, Amazon Registra Inc, Hostinger, ...)

• The Domain Registrar usually provides you with a DNS service to manage your DNS records

• But you can use another DNS service to manage your DNS records

• Example: purchase the domain from GoDaddy and use Route 53 to manage your DNS records

• So if you buy your domain on a 3rd party registrar, you can still use Route 53 as the DNS Service provider

• Create a Hosted Zone in Route 53

• Update NS Records on 3rd party website to use Route 53 Name Servers