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

Network Address Translation (NAT) primarily serves the purpose of hiding the internal network architecture of an organization from the external network, specifically the internet. By converting private IP addresses used within a local network into a single public IP address, NAT acts as a mediator for traffic that goes in and out of the network. This process not only masks the details of the internal IP structure from external entities but also adds a layer of security by limiting direct access to internal devices.

Utilizing NAT, organizations can effectively manage their IP address space more efficiently, avoid IP address exhaustion, and create a more secure network environment because external users cannot see the specific addresses of internal devices. This can significantly diminish the public visibility of internal systems, making it harder for attackers to identify and target individual machines within the network.

The other options like improving network speed or controlling user access do not accurately describe NAT's primary functionality. While NAT may lead to some performance improvements due to fewer routings on public networks, its core purpose remains the safeguarding of the internal network's structure and visibility. Security transmission pertains more to encryption techniques rather than the address translation function of NAT.