IPsec operates at which layer in the network stack?

IPsec operates at which layer in the network stack?

• A. Data link layer
• B. Transport layer
• C. Network layer
• D. Application layer

Answer: (C)

IPsec operates at the network layer. It secures IP packets as they travel between hosts across IP networks, independent of the transport-layer protocols in use. The security is applied to the IP packet itself, not to the higher-layer data. IPsec supports two modes: transport mode, which protects the payload of the IP packet while leaving the IP header mostly intact, and tunnel mode, which encapsulates the entire original IP packet inside a new IP packet. The built-in protocols, AH and ESP, provide authentication/integrity and confidentiality (ESP) as part of this processing, reinforcing why the protection belongs at the network layer rather than the data link, transport, or application layers.

IPsec operates at the network layer. It secures IP packets as they travel between hosts across IP networks, independent of the transport-layer protocols in use. The security is applied to the IP packet itself, not to the higher-layer data. IPsec supports two modes: transport mode, which protects the payload of the IP packet while leaving the IP header mostly intact, and tunnel mode, which encapsulates the entire original IP packet inside a new IP packet. The built-in protocols, AH and ESP, provide authentication/integrity and confidentiality (ESP) as part of this processing, reinforcing why the protection belongs at the network layer rather than the data link, transport, or application layers.