What protocol is typically used for securing data moves over a VPN?

IPSec, or Internet Protocol Security, is a protocol suite designed specifically for securing Internet Protocol (IP) communications through authenticating and encrypting each IP packet within a communication session. It is widely used in Virtual Private Networks (VPNs) to ensure that data transmitted over the internet remains confidential, integral, and authentic.

By implementing Encryption and Integrity checks, IPSec can protect data that is being transmitted across potentially insecure networks, such as the internet. It provides multiple services, including encryption to protect data confidentiality, authentication to ensure that the data originates from a trusted sender, and integrity checking to verify that the data has not been altered in transit.

The other options do not serve this particular function as effectively as IPSec in the context of VPN security. For instance, PPP (Point-to-Point Protocol) is primarily a data link layer protocol used for direct connections between two nodes over a serial link. SCM (Security Content Management) relates to security policies rather than data transmission, and SMTP (Simple Mail Transfer Protocol) is specifically used for sending and receiving emails, not for securing data at the network level. Therefore, IPSec is the correct choice for securing data over a VPN.