Examkin

Question

Difficulty: Very hardRoute 53 Routing Policies and DNS Failover Strategies

A company is designing a high-availability, active-active web application deployed across two AWS Regions: us-east-1 and eu-west-1. The application is accessed via the domain apex (example.com). The architecture requires low-latency access for global users by directing them to the nearest healthy region. Additionally, the system must support automatic failover to the secondary region if either the load balancer target servers become unhealthy or the local application instance loses connectivity to its database. Which two configurations should the solutions architect implement to meet these requirements?

  1. Create Route 53 Latency Alias records for example.com pointing to the Application Load Balancer (ALB) in each region, and enable the Evaluate Target Health option.Answer
  2. Create Route 53 HTTPS health checks to monitor the application's database connectivity endpoint in each region, and associate these health checks with their corresponding Latency Alias records.Answer
  3. C
    Create Route 53 Latency CNAME records for example.com pointing to the DNS names of the ALBs, and configure a TTL of 10 seconds to minimize failover latency.
  4. D
    Create a Route 53 Failover routing policy designating the primary region as primary and the secondary region as secondary, and configure latency-based routing within the primary failover group.
  5. E
    Create Route 53 Latency Alias records pointing directly to the Amazon RDS database endpoint in each region, and configure Route 53 health checks to trigger an RDS replica promotion.

Answer

Creating Route 53 Latency Alias records pointing to the Application Load Balancers with target health evaluation enabled, and configuring custom Route 53 HTTPS health checks to monitor the database connectivity endpoint.
The correct solution requires configuring Route 53 Latency Alias records pointing to the Application Load Balancer in each region and setting 'Evaluate Target Health' to Yes. This allows traffic to be routed to the closest healthy region at the zone apex. Additionally, to detect database connectivity failures, custom Route 53 HTTPS health checks must be created to query the database connectivity endpoint and associated with the Latency Alias records.

Step-by-Step Solution

1
Address the requirement for zone apex routing and active-active low-latency routing.
Determine that Route 53 Latency Alias records pointing to the ALBs in each region must be used, as CNAME records cannot reside at the zone apex.
Alias records map the zone apex directly to AWS resources like ALBs and support Route 53's active health monitoring.
2
Configure automatic load balancer health evaluation.
Enable the 'Evaluate Target Health' option on the Latency Alias records.
This permits Route 53 to check the health of the ALB targets and stop routing traffic to a region if its web servers fail.
3
Address the requirement to monitor backend database connectivity and handle regional degradation.
Create custom HTTP/HTTPS Route 53 health checks probing a health endpoint that verifies database connectivity, and associate these health checks with the Latency Alias records.
ALB Target Group checks might not capture deep backend dependency failures, so custom health checks are required for end-to-end failover.

Key Concept

Combining Route 53 Latency Routing, Alias Records, and Multi-layered Health Checks for Active-Active Failover at the Zone Apex
Rate this question

Topics

Route 53 Routing Policies and DNS Failover Strategies

More questions from this topic