What is NAT overload (PAT) and why is it beneficial for home networks?

• A. It allows multiple internal devices to share a single public IP by multiplexing ports, conserving public addresses.
• B. It assigns a unique public IP to each internal device.
• C. It disables port multiplexing to simplify routing.
• D. It translates only MAC addresses.

Answer: (A)

NAT overload (PAT) works by letting many devices inside your home share one public IP. When an internal device connects to the internet, the router translates its private IP and port into the router’s public IP plus a unique source port for that connection. The router keeps track of each mapping, so when a reply comes back, it can direct it to the correct internal device. This port multiplexing is what lets dozens or hundreds of internal devices use a single public address.

The key benefit is address conservation: you don’t need a public IP for every device, which saves money and makes home networks simpler to set up because everything can pass through one gateway. It’s also why most homes use private addressing behind a single public address supplied by the ISP.

It isn’t giving each internal device its own public IP, which would be static or one-to-one NAT. It doesn’t disable port multiplexing—PAT relies on using different ports to distinguish connections. And it doesn’t translate only MAC addresses; NAT operates at the IP layer, translating addresses (and ports) to manage traffic between internal devices and the internet.