A startup on a tight budget runs instances in private subnets across two AZs. They want outbound internet access while minimizing cost, accepting some availability risk. Which design reflects the cost-optimized choice (and its tradeoff)?
A) One NAT Gateway in a single AZ, used by both AZs’ private subnets.
B) One NAT Gateway per AZ.
C) No NAT Gateway; give every instance a public IP.
D) Route all traffic through an on-premises firewall.
Correct Answer: A
Explanation: A single NAT Gateway shared across AZs minimizes cost; the tradeoff is that if that AZ fails, the other AZ loses outbound internet — acceptable for a budget-conscious startup. (B) is the resilient but pricier option. (C) exposes instances publicly. (D) adds latency, complexity, and likely cost.