In order to protect a network against unauthorized external connections to corporate systems, the information
security manager should BEST implement:

A.
a strong authentication.

B.
IP antispoofing filtering.

C.
network encryption protocol.

D.
access lists of trusted devices.

Explanation:

Strong authentication will provide adequate assurance on the identity of the users, while IP antispoofing is aimed at the device rather than the user. Encryption protocol ensures data confidentiality and authenticity while access lists of trusted devices are easily exploited by spoofed identity of the clients.