networking

To design a secure AWS VPC topology, plan a three-tier subnet model across multiple AZs using public, private, and isolated subnets. Implement security groups and NACLs to establish strict security boundaries, and configure gateway endpoints for S3 and DynamoDB access.

The best way to connect multiple VPCs is using Transit Gateway patterns and VPC peering. These approaches enable scalable, secure connectivity across VPCs and regions while maintaining isolated network boundaries and managing Route53 DNS strategies.

Use security groups for stateful instance-level protection and NACLs for stateless subnet-level network boundary protection. Combining both creates defense-in-depth security boundaries that enforce strict traffic filtering across your VPC subnets.

Troubleshoot multi-AZ network connectivity issues by validating VPC route tables, security group rules, and NACL configurations. Check Transit Gateway routing, VPC peering connections, and Route53 DNS resolution to isolate and resolve cross-AZ traffic blockages.

NAT gateways allow private subnets to access the internet, but for AWS services like S3 and DynamoDB, configure VPC gateway endpoints instead. This ensures secure, scalable connectivity without exposing isolated subnets to public internet routes.

Yes, you can plan CIDR blocks for a three-tier subnet model by allocating non-overlapping IP ranges across multiple AZs. This VPC design principle ensures scalable subnet layouts for public, private, and isolated tiers without IP exhaustion.