Your company has computers in multiple locations that use IPv4 and IPv6. Each location is protected
by a firewall that performs symmetric NAT. You need to allow peer-to-peer communication between
all locations. What should you do?

A.
Configure dynamic NAT on the firewall.

B.
Configure the firewall to allow the use of Teredo.

C.
Configure a link local IPv6 address for the internal interface of the firewall.

D.
Configure a global IPv6 address for the external interface of the firewall.

Explanation:
In computer networking, Teredo is a transition technology that gives full IPv6 connectivity for Ipv6-
capable hosts which are on the IPv4 Internet but which have no direct native connection to an IPv6
network. Compared to other similar protocols its distinguishing feature is that it is able to perform
its function even from behind network address translation (NAT) devices such as home routers.
http://en.wikipedia.org/wiki/Teredo_tunneling