You are working as a SysOps administrator for a large multinational organization.
They have a set of critical web servers spread across the globe.
For Web servers in us-east-1 region & us-west-1 region, you have configured latency-based routing followed by weighted routing policy between web servers in different AZ.
These Web servers are behind ELB.
Alias records are created using Route 53 pointing web server domain to this ELB.
During failover testing you are observing that traffic is not shifting to us-west-1 post all instance down in us-east-1 region.What might be a possible reason for this?
Click on the arrows to vote for the correct answer
A. B. C. D.Correct Answer: C.
In case of complex routing policy for Route 53, a health check for all records alias & non-alias is necessary.
Route 53 will assume it's working & traffic is not diverted to healthy instance for missing health check.
In the above case, health check evaluation should be enabled for alias records in us-east 1
When all instances in this region are down, traffic will be shifted to servers in us-west-1.
Option A is incorrect as If a Health check is being configured on Route 53, additional health checks on ELB are not required.
Option B is incorrect as in this case, latency routing is used to shift traffic between 2 regions & weighted routed policy between instances in different AZ of each region.
With health checks missing, a failover policy will not be useful in this case.
Option D is incorrect as Route 53 is a global service, no need to specify Region while creating a Health check.
For more information on health checks for complex routing, refer to the following URL-
https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/dns-failover-complex-configs.htmlThe possible reason for traffic not shifting to us-west-1 post all instances down in us-east-1 region could be:
B. Routing Policy is misconfigured. Failover routing should be used instead of a weighted routing policy.
Explanation:
The given scenario describes that latency-based routing has been configured between the web servers in us-east-1 and us-west-1 regions. Latency-based routing is a routing policy in Route 53 that selects the region with the lowest latency for the user. Weighted routing policy is used between web servers in different Availability Zones within a region, and it distributes traffic among them based on the specified weights.
In a failover scenario, the routing policy should be configured as a failover routing policy. Failover routing policy is used when you want to route traffic to a standby region when the primary region becomes unavailable. When a failover routing policy is used, Route 53 automatically monitors the health of the primary endpoint using health checks, and if it detects a problem, it routes traffic to the secondary endpoint.
Therefore, the possible reason for traffic not shifting to us-west-1 post all instances down in us-east-1 region could be that the routing policy is misconfigured. The weighted routing policy is not designed for failover scenarios, and the Route 53 health checks are not sufficient to detect and route traffic to the secondary endpoint.
Option A is incorrect because health checks for ELB in the US-east-1 region are not relevant to failover routing.
Option C is incorrect because the Target Health check in Alias records is used to monitor the health of the endpoints and not for failover routing.
Option D is incorrect because Route 53 health checks are not relevant to the current routing policy.