Security, Identity, and Compliance
CoreNetwork ACLs
Explicit VPC configuration/troubleshooting and stateless filtering.
Key points
- NACLs are ordered stateless subnet filters whose rules must permit both directions of an allowed flow.
Best-known use cases
- D4.1, D4.2, and D5.1: allow or deny the named subnet flow, including service and ephemeral return ports.
What candidates often confuse it with
- NACLs are stateless and support allows and denies; security groups are stateful allow controls on resource interfaces.
Key takeaway
When a reply is dropped at a subnet boundary, inspect both NACL directions before changing a stateful security group.
Related services
- AWS Certificate Manager (ACM)
- Amazon EC2 security groups
- Egress-only internet gateways
Relevant exam tasks
- D4.1 — Task 4.1: Implement and manage security and compliance tools and policies.
- 4.1.1 — Implement IAM features (for example, password policies, multi-factor authentication [MFA], roles, federated identity, resource policies, policy conditions).
- D4.2 — Task 4.2: Implement strategies to protect data and infrastructure.
- 4.2.1 — Implement and enforce a data classification scheme.
- D5.1 — Task 5.1: Implement and optimize networking features and connectivity.
- 5.1.1 — Configure a VPC (for example, subnets, route tables, network ACLs, security groups, NAT gateways, internet gateway, egress-only internet gateway).