What is the purpose of Network Address Translation (NAT)?

The primary purpose of Network Address Translation (NAT) is to map private IP addresses to public addresses for Internet routing. This is particularly important in environments where multiple devices within a local network use private IP addresses, which are not routable on the internet. NAT allows these devices to communicate with external networks by providing a single public IP address that can represent all the private IPs within the network.

When data packets from a device with a private IP address need to be transmitted over the Internet, NAT modifies the source address in the packet header to the public IP address allocated to the local network. When responses come back from the Internet, NAT tracks these communications and translates the public IP address back to the corresponding private IP address, ensuring the data reaches the correct internal device.

This process effectively conserves the limited number of available public IPv4 addresses and enhances security by hiding the internal structure of the local network from external users. The other options provided do not accurately describe the fundamental role of NAT. For instance, while NAT involves address translation, it does not inherently assign IP addresses automatically, nor does it encrypt data packets.