NAT was introduced primarily to alleviate what issue related to IPv4?

NAT, or Network Address Translation, was introduced primarily to address the issue of address space congestion within the IPv4 protocol. When IPv4 was developed, it allowed for approximately 4.3 billion unique addresses, which at the time seemed sufficient. However, due to the exponential growth of the internet and the increasing number of devices requiring IP addresses, this address pool became almost entirely exhausted.

NAT provides a solution to this issue by allowing multiple devices on a local network to share a single public IP address. This means that private IP addresses can be used within a local network, while NAT translates these private addresses into a public address for communication over the internet. By enabling this form of address reuse, NAT significantly reduces the demand for public IP addresses, thereby alleviating the congestion in address space for IPv4.

This effectively allows continued growth and scaling of networks without the immediate need for new public IP addresses, which is crucial in managing the limited IPv4 address space.