Question

A company runs a chatty microservices application on EC2 across three Availability Zones in a single Region. The services exchange large volumes of traffic with each other continuously. The finance team notices a large and growing line item for inter-AZ data transfer on the monthly bill. The architecture must remain highly available, but the team wants to reduce these data transfer costs. Which approach best reduces the inter-AZ transfer charges while preserving availability?

Accepted Answer

Use placement groups and topology-aware routing so that most service-to-service traffic stays within the same Availability Zone, while keeping instances spread across AZs for failover.

Answer

Consolidate all microservices instances into a single Availability Zone to eliminate all inter-AZ data transfer charges.

Answer

Route all inter-service traffic through a NAT gateway so the traffic is billed at the lower NAT processing rate.

Answer

Enable VPC peering between the subnets in each Availability Zone to remove data transfer charges for intra-Region traffic.