What encryption protocol is typically used in IPSec VPN?

The correct choice highlights the encapsulation methods used within IPSec VPNs, specifically Authentication Header (AH) and Encapsulation Security Payload (ESP). These protocols serve distinct functions in the context of IPSec.

AH provides integrity and authenticity for the data packets, ensuring that the data hasn’t been altered in transit and confirming the identity of the sender. However, it does not provide encryption; therefore, it can be thought of as adding a layer of security that verifies the content's integrity.

ESP, on the other hand, focuses on confidentiality and security by encrypting the content of the packets, as well as providing integrity and authenticity similar to what AH offers. This makes ESP more comprehensive for scenarios where data privacy is crucial, as it secures the data payload from eavesdroppers.

By combining these two protocols, IPSec effectively secures communication by ensuring both confidentiality and authenticity, fulfilling the necessary requirements for establishing a secure VPN connection. Therefore, choosing this option accurately reflects the primary protocols utilized in an IPSec VPN setup.