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SC.L1-3.13.5Public-Access System Separation

Level 1
FAR 52.204-21 b.
800-171: 3.13.5

>Control Description

Implement subnetworks for publicly accessible system components that are physically or logically separated from internal networks.

>Cross-Framework Mappings

NIST SP 800-171

>Assessment Interview Topics

Questions assessors commonly ask

Process & Governance:

  • What is your policy for separating public-facing systems from internal networks?
  • How do you implement and enforce network segmentation?
  • What is your process for approving new public-facing systems?
  • Who is responsible for ensuring proper network separation?
  • How do you verify that separation is effective?

Technical Implementation:

  • What network segmentation separates public-facing systems?
  • What DMZ or screened subnet architectures are implemented?
  • What VLANs or physical separation is used?
  • What access controls restrict traffic between public and internal networks?
  • What monitoring detects unauthorized connections between zones?

Evidence & Documentation:

  • What network diagrams show boundary protection architecture?
  • What firewall rule sets and configurations can you provide?
  • What encryption implementation documentation shows FIPS-validated crypto?
  • What key management procedures can you provide?
  • What network segmentation documentation shows proper separation?
  • What evidence shows cryptographic mechanisms protect CUI?
  • What configuration documentation shows security controls are properly implemented?

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