NAT routers are used to translate private (not globally unique) addresses on an internal network into public or legal addresses before packets are forwarded to another network.
A key feature is that NAT can be configured to only advertise one address for the entire network to the outside world. This provides additional security by effectively hiding the entire internal network behind that address.
NAT therefore serves the dual functions of security and minimizing the number of IP addresses used and is typically implemented in remote-access environments.
Vulcan is ideal for testing the performance and functionality of NAT routers.