You are a security consultant for a company that has a location in Houston, Texas, New York City, and Dallas, Texas. Your client requires link to link communications from the LAN to the WAN for data/traffic encryption supported by IP that includes encryption and authentication. They will be using L2TP at L3 of the OSI model. The CIO for the company plans to migrate to IPv6 over the next year so he needs something that will be compatible with IPv6. What is the BEST protocol to use for your client? A. IPSec Transport mode B. IPSec Tunnel model C. PPTP D. L2F Solution B. IPsec in tunnel mode provides link encryption, is compatible with IP v6 and can be used to encrypt any traffic supported by IP .