A NAT gateway enables multiple devices on a local network to access the Internet using a single public IP address. This is important for conserving IP addresses and enhancing security by masking internal IP addresses from external networks. The role of translating the internal private IP addresses to a public IP allows seamless communication with the Internet. NAC (Network Access Control) is responsible for controlling access to the network based on policies, A DHCP server assigns dynamic IP addresses within the network, and An Internet gateway provides a routing path from the internal network to the global Internet but does not perform address translation which is specific to NAT.