What is NAT (Network Address Translation)?
NAT, or Network Address Translation, is how one public internet address is shared by many devices. Your router holds the single public IP; every phone, laptop and CCTV camera behind it uses private addresses like 192.168.1.x. As traffic passes out, the router rewrites the source address to its public IP and keeps a table to route replies back to the right device.
NAT exists because public IPv4 addresses are scarce — India's ISPs even layer it twice (CGNAT), sharing one public IP among many customers, which is why port forwarding to a home DVR often fails on ordinary connections. For businesses, understanding NAT explains everyday puzzles: why the whole office shows one IP to websites, why hosting anything needs port forwarding or a static IP, and why some multiplayer or VoIP apps struggle.