Which of the following statements about IPsec is true?

• A. IPsec can be used to secure network communications between two machines
• B. IPsec can be used to secure network communications between two networks
• C. IPsec network traffic is always encrypted
• D. IPsec cannot provide authentication

Answer: (A)

IPsec protects IP traffic by providing authentication, integrity, and optional confidentiality. It can be used in host-to-host deployments, where two machines communicate securely and at minimum ensure the data is authenticated and protected from tampering. It can also secure traffic between networks (site-to-site) when running in tunnel mode, which is another common use case.

The idea that traffic is always encrypted isn’t accurate, because IPsec can be configured to provide only authentication and integrity (using AH) without encryption, depending on the setup. Likewise, IPsec does provide authentication, so the statement claiming it cannot is incorrect.