Which protocol is an extension of PPP used for VPN tunneling?

Which protocol is an extension of PPP used for VPN tunneling?

• A. PPTP
• B. L2TP
• C. IPSec
• D. SSH

Answer: (A)

PPP provides the method for a direct, point-to-point link with authentication and other features. For VPN tunneling, you need to carry those PPP frames across an IP network, which is achieved by encapsulating them in a dedicated tunnel protocol. The protocol designed for that purpose is PPTP—the Point-to-Point Tunneling Protocol. It extends PPP to create a VPN tunnel by wrapping PPP frames and transporting them over an IP network, using a control channel to set up the tunnel and GRE to carry the PPP payload. This makes PPTP the best fit for an extension of PPP used specifically for VPN tunneling. Other options aren’t extensions of PPP in the same way: Layer 2 Tunneling Protocol is a separate tunneling mechanism that can carry PPP frames but isn’t an intrinsic PPP extension; IPSec is a suite that secures IP traffic, not a PPP-tunneling extension; SSH is for secure remote access, not VPN tunneling built on PPP.

PPP provides the method for a direct, point-to-point link with authentication and other features. For VPN tunneling, you need to carry those PPP frames across an IP network, which is achieved by encapsulating them in a dedicated tunnel protocol. The protocol designed for that purpose is PPTP—the Point-to-Point Tunneling Protocol. It extends PPP to create a VPN tunnel by wrapping PPP frames and transporting them over an IP network, using a control channel to set up the tunnel and GRE to carry the PPP payload. This makes PPTP the best fit for an extension of PPP used specifically for VPN tunneling.

Other options aren’t extensions of PPP in the same way: Layer 2 Tunneling Protocol is a separate tunneling mechanism that can carry PPP frames but isn’t an intrinsic PPP extension; IPSec is a suite that secures IP traffic, not a PPP-tunneling extension; SSH is for secure remote access, not VPN tunneling built on PPP.