IPsec operates at the internet layer.

• A. True
• B. False
• C. Not specified
• D. Depends on implementation

Answer: (A)

IPsec operates at the Internet layer because it secures IP packets as they are processed by the IP layer, sitting between IP and the higher-layer protocols in the TCP/IP model. It protects traffic by providing two main components: AH for data integrity and authentication, and ESP for confidentiality and integrity. IPsec can work in transport mode, which protects the payload of a specific transport protocol without changing the IP header, or in tunnel mode, which wraps the entire original packet inside a new IP packet. This design lets IPsec secure any upper-layer protocol regardless of the application, and it is not limited to a particular transport protocol. Therefore, stating that IPsec operates at the internet layer is correct.