Route53] About Failover Method
We want to increase application redundancy and reliability by configuring DNS routing for EC2 instances to avoid traffic to instances that are experiencing anomalies. If no anomalies are occurring, we will use the redundant application configuration equally.
ACTIVE ACTIVE configuration in DNS failover settings
You can configure failover (active/active and active/passive) using Route 53 health checks; Route 53 checks the health of resources when there are multiple resources, such as EC2 instances performing the same function, and responds to DNS queries using only the normal resources. You can configure Amazon Route 53 to check the health of resources and respond to DNS queries using only those resources that are healthy.
Specifically, assume that the example.com site is hosted on six servers, two in each of three data centers around the world.
You can configure Route 53 to check the health of those servers and respond to DNS queries for example.com using only the servers that are healthy at that time
The active/active configuration of the DNS failover settings allows equal use of all configured resources. If a resource becomes unavailable, it will be detected by Route 53 as an anomaly and henceforth will be withheld from inclusion in responses to queries.
The active/passive configuration in the failover setup ensures that the primary resource is always available, but puts a secondary resource or resource group on standby in case all primary resources become unavailable.
To configure DNS failover using Route 53, specify the type of record to create (weighted alias, failover, latency, etc.) on a per-node basis.
This means that failover can be configured for routing policies that are not failover routing.
About Failover Routing
Route53 failover routing is not able to distribute incoming requests evenly across all EC2 instances
Using Route53's location-based routing, you can select resources to handle traffic based on the user's location, i.e., the originating location of the DNS query.
For example, all queries from Europe could be routed to the ELB load balancer in the Norway region, while queries from Asia could be configured to route to the ELB load balancer in the Tokyo region.