A VPN uses an IP $\_\_\_\_\_\_\_\_\_\_$ protocol and security services that is transparent to the network users.

A$)$Proxy

B$)$ Session

C$)$ UDP

D$)$ Tunneling

A layer $3$ switch is essentially a

A$)$ switch and router combined into one package.

B$)$ switch and hub combined into one package.

C$)$ switch that uses MAC addresses at layer $3.$

D$)$ router that uses IP addresses at layer $2.$