A company has implemented PPTP as a VPN solution. Which of the following ports would need to be opened
on the firewall in order for this VPN to function properly? (Choose two.)

A.
UDP 1723

B.
TCP 500

C.
TCP 1723

D.
UDP 47

E.
TCP 47

Explanation:
A PPTP tunnel is instantiated by communication to the peer on TCP port 1723. This TCP connection is then
used to initiate and manage a second GRE tunnel to the same peer. The PPTP GRE packet format is nonstandard, including an additional acknowledgement field replacing the typical routing field in the GRE header.
However, as in a normal GRE connection, those modified GRE packets are directly encapsulated into IP
packets, and seen as IP protocol number 47.