Which of the following is not typically considered a NAT traversal technique?

• A. UPnP
• B. STUN
• C. TURN
• D. DMZ

Answer: (D)

NAT traversal techniques are methods that help devices behind a NAT reach and be reached by peers on the internet, often by discovering the public address, opening necessary ports, or relaying traffic when a direct path isn’t possible. UPnP lets a device automatically punch holes by requesting the router to map a port for it, removing manual configuration barriers. STUN helps a device learn its public address and NAT behavior so it can decide how to connect to others or whether to use a relay. TURN provides a relay server to route traffic when a direct peer-to-peer path can’t be established, ensuring connectivity even with restrictive NATs.

DMZ isn’t a NAT traversal technique. It’s a network setup that forwards all ports to a single internal host, effectively exposing that host to the internet. While this can bypass NAT for that one device, it isn’t a portable, standard method for enabling two devices behind NATs to communicate, and it carries significant security risks.