AWS Certified Advanced Networking Specialty Practice Exam

To secure the traffic flowing between VPCs in different accounts, using VPC Peering connections with proper security group and Network Access Control List (NACL) configurations is an effective approach. VPC peering allows two VPCs, even in different accounts or regions, to communicate as if they are within the same network, enabling private IP addresses for connectivity.

By configuring security groups, you can define rules that control the inbound and outbound traffic to instances within the VPCs, ensuring that only authorized traffic is allowed. NACLs further enhance security by providing a stateless layer of control that governs the traffic entering or exiting a subnet. Using these security measures together ensures that data remains secure and protected while in transit between VPCs.

While VPN connections and Direct Connect can be secure options for connecting VPCs, using VPC Peering provides a more direct and low-latency connection that is ideal for establishing private linkages between accounts. IAM policies, while vital for securing AWS resources, do not directly manage or secure traffic between VPCs, making them less relevant for this specific use case.