Which technology allows multiple computers on an internal network to share one public address?

Network Address Translation (NAT) is a technology that enables multiple devices on a local network to share a single public IP address when accessing the internet. This is achieved by translating the private IP addresses of internal devices to the public IP address as they send and receive data.

When a device on the internal network sends a request to the internet, NAT modifies the outgoing packet to replace its private IP address with the public IP address assigned to the router or gateway. When the response returns, NAT translates the public address back to the appropriate private address, ensuring that the data reaches the correct internal device. This not only conserves the limited number of available public IP addresses but also provides a layer of security by hiding the internal network’s structure from external entities.

The alternative options serve different purposes: a VPN establishes a secure connection over the internet, a firewall controls incoming and outgoing network traffic based on predetermined security rules, and a proxy server acts as an intermediary for requests from clients seeking resources from other servers. While each of these plays a role in network security and management, they do not provide the functionality of allowing multiple devices to share a single public IP address, which is the central feature of NAT.