ANS-C01 Question 370
Select 3You are managing a multi-region application hosted on EC2 instances behind Application Load Balancers (ALBs) in two different AWS regions. The application users are reporting high latency when accessing the service in one region. Upon investigation, you find that cross-region communication between the instances is required, and you need to optimize the network performance and mitigate reachability constraints. Which actions should you take to address this issue?
- A
Enable VPC peering between the VPCs in the two regions and adjust the MTU (Maximum Transmission Unit) to 8500 bytes for all instances.
- B
Use AWS Global Accelerator to route user traffic to the closest healthy endpoint while maintaining low latency.
- C
Configure an AWS Transit Gateway with peering attachments between the two regions to optimize inter-region traffic.
- D
Investigate the source of latency by using Amazon CloudWatch metrics and enabling VPC Flow Logs for both VPCs.
- E
Switch to IPv6 for all traffic between the two regions and ensure that security groups and network ACLs allow IPv6 communication.
Show answer and explanation
Correct answers: B, C, D
Explanation
To address high latency and reachability constraints in a multi-region setup, multiple solutions are required. AWS Global Accelerator optimizes user traffic routing, reducing latency for end users. AWS Transit Gateway provides efficient inter-region traffic routing, and CloudWatch metrics and VPC Flow Logs help diagnose the root cause of network performance issues. VPC peering and IPv6 are less suitable in this scenario as they do not directly address the specific performance optimization required.
- A. Incorrect.
VPC peering does enable communication between VPCs, but it does not provide optimized routing for cross-region traffic. Additionally, setting the MTU to 8500 bytes is not supported for most AWS services and could cause packet fragmentation issues.
- B. Correct.
AWS Global Accelerator is specifically designed to optimize network performance for end-user traffic by routing requests to the nearest healthy region. This is a valid solution to reduce latency.
- C. Correct.
AWS Transit Gateway with peering attachments provides an efficient, scalable way to route inter-region traffic. This is a recommended approach for optimizing cross-region communication.
- D. Correct.
Amazon CloudWatch metrics and VPC Flow Logs help identify the source of latency. These tools are crucial for diagnosing network performance issues and making informed decisions.
- E. Incorrect.
Switching to IPv6 may improve certain scenarios, but the question specifically focuses on optimizing cross-region communication and addressing latency. IPv6 alone does not directly solve the problem.