Authentication and Authorization (often abbreviated as AuthN and AuthZ) are foundational pillars of access control in network security:

Authentication (AuthN):Verifies "who you are" by validating credentials against a trusted source. Examples include passwords, MFA (multi-factor authentication), certificates, or biometrics. It ensures the entity (user, device) is legitimate, typically via protocols like Kerberos or LDAP.

Authorization (AuthZ):Determines "what you can do" after authentication, enforcing policies on resource access (e.g., read/write permissions, API calls). It relies on mechanisms like Access Control Lists (ACLs), Role-Based Access Control (RBAC), or Attribute-Based Access Control (ABAC).

Option Acorrectly separates these roles:

Authorization governs access decisions (e.g., "Can user X read file Y?").

Authentication establishes identity (e.g., "Is this user X?").

In practice, these processes are sequential: AuthN precedes AuthZ. For example, logging into a VPN authenticates your identity (e.g., via username/password), then authorizes your access to specific subnets based on your role. CNSP likely stresses this distinction for designing secure systems, as conflating them risks privilege escalation or identity spoofing vulnerabilities.

Why other options are incorrect:

B:Reverses the definitions—Authentication doesn’t grant/deny access (that’s AuthZ), and Authorization doesn’t validate identity (that’s AuthN). This mix-up could lead to flawed security models.

C:Falsely equates AuthN and AuthZ and attributes access rules to AuthN. They’re distinct processes; treating them as identical undermines granular control (e.g., NIST SP 800-53 separates IA-2 for AuthN and AC-3 for AuthZ).

D:Misassigns access control to AuthN and claims they don’t interoperate, which is false—they work together in every modern system (e.g., SSO with RBAC). This would render auditing impossible, contradicting security best practices.

Real-World Context:A web server (e.g., Apache) authenticates via HTTP Basic Auth, then authorizes via .htaccess rules—two separate steps.References:CNSP Official Study Guide (Access Control Fundamentals); NIST SP 800-53 (Security and Privacy Controls).