What is NAT (Network Address Translation)?
Why Interviewers Ask This
This question tests conceptual clarity. Interviewers want to hear a precise, confident definition before moving to more complex Networking topics. It also reveals how well you can explain technical ideas to non-experts.
Answer
NAT (Network Address Translation) is a technique that modifies IP address information in packet headers while in transit through a router. It allows multiple devices on a private network to share a single public IP address when communicating with the Internet. Your home router has one public IP from your ISP but assigns private IPs (192.168.x.x) to all your devices. When you access a website, the router replaces your private IP with its public IP in the outgoing packet (and remembers the mapping in a NAT table). When the reply comes back, the router translates the public IP back to the correct private IP. PAT (Port Address Translation), also called NAPT, extends NAT by using port numbers to distinguish between multiple simultaneous connections sharing one public IP — this is what virtually all home routers use.
Pro Tip
Before answering, structure your response: one-line definition → real-world analogy → concrete example from a project. This makes even complex Networking answers easy to follow.