Which of the following protects against unauthorized access to confidential information via encryption and works at the network layer? (ISC)2 CISSP-ISSAP Exam

Question

Options

• AFirewall
• BNAT
• CMAC address
• DIPSec

• A
  3% (1)
• B
  3% (1)
• C
  9% (3)
• D
  84% (27)

Explanation

IPSec is the only option that explicitly provides encryption while operating at Layer 3 (Network Layer) of the OSI model. It secures IP packets end-to-end using protocols like AH (Authentication Header) and ESP (Encapsulating Security Payload), protecting confidentiality, integrity, and authenticity of data in transit.

• Firewall (A) filters traffic based on rules but does not encrypt data - it controls access, not confidentiality.
• NAT (B) translates IP addresses between private and public networks; it obscures internal topology but provides no encryption.
• MAC address (C) is a Layer 2 (Data Link) identifier for network interfaces - it has nothing to do with encryption or confidentiality protection.

Memory tip: Break it down - IPSec = security at the IP layer. If a question mentions "encryption + network layer" together, IPSec is almost always the answer. VPNs commonly use IPSec for exactly this reason.

No community discussion yet for this question.