A large mobile telephony and data network operator has a data center that houses network elements. These are essentially large computers running on Linux. The perimeter of the data center is secured w

Even with perimeter security, internal network elements running Linux must be hardened with robust user authentication (user IDs and strong passwords) and subjected to regular security tests (like vulnerability scanning and penetration testing). This ensures layered security, protecting against insider threats, compromised perimeter defenses, and unpatched vulnerabilities on the hosts themselves.

Relying solely on physical access control is insufficient; logical security, including user authentication and regular testing, is crucial for securing network elements against remote attacks or compromised insiders.

Perimeter defenses like firewalls and IPS protect the network boundary but do not eliminate the need for host-level security measures on individual network elements, as these can still be exploited if unhardened.

While disaster recovery is important, this option describes a strategy for business continuity rather than a specific security policy for hardening the network elements themselves.