There is(are) ________ NAT traversal method(s).

• A. 1
• B. 2
• C. 7
• D. several

Answer: (D)

NAT traversal uses a range of techniques to let devices behind NATs communicate with each other. There isn’t a single fixed method; multiple approaches exist and are used in different situations. STUN helps peers discover their public-facing address and NAT behavior so a direct path can sometimes be established. If direct connectivity fails, TURN can relay traffic through a server. ICE provides a framework to collect candidate paths and choose the best one, often leveraging STUN and TURN. Hole punching techniques attempt to open a path through NATs by coordinating how peers send packets. Additionally, port-mapping methods like UPnP, NAT-PMP, and PCP help devices punch holes in their NATs. Because there are several distinct techniques and combinations in use, “several” is the best answer.