Answer:
The answer is the point - to -point protocol, which allows user to set a secure VPN connection for client and server connectivity.
Explanation:
A virtual private network is a private-public network because of encryption and tunneling to ensure the integrity of the data. VPN requires a tunnel to work and encryption.
In VPNs, there are different protocols can be used, such as point- to - Point Tunneling Protocol (PPTP), IPSec, and L2TP.
Point to Point Protocol is a Microsoft protocol which allows user to set a connection and secure VPN destination. Point to point protocol is designed for client and server connectivity. It developed a connection between two computers. The data link layer that transmits over IP networks is used for point to point tunneling.
Such as option A is not correct because it is distracter and IPSecis primary tunneling protocol. It supports only IP networks. L2TP is not a VPN but extend VPN over the various network.