Suppose you have been hired as a security consultant in a large organization ABC.org, which has offices in three different countries: New Zealand, the USA, and the UK. This organization wishes to use a VPN (Virtual Private Network) for internal employees. This organization has decided to use IPSec-powered VPN. This organization also uses NAT (Network Address Translation) and multiple network firewalls.

(a) Suggest whether the tunnel mode or the transport mode is better for the organization's VPN. Justify your answer.

(b) Suggest whether the AH or ESP protocol is better for the organization's VPN. Justify your answer.