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

• A. To translate a private IP address to a public IP address and vice versa.
• B. To assign IP addresses to devices automatically.
• C. To encrypt packets for secure transmission.
• D. To filter traffic based on port numbers.

Answer: (A)

NAT exists to let devices on a private network reach the Internet by changing their private addresses to a public one (and doing the reverse for incoming traffic). When a private device sends a packet, the NAT device rewrites the source IP to its public address and keeps track of that translation so replies can be delivered back to the correct internal device. This lets many devices share a single public IP, conserving IPv4 addresses and keeping internal addressing hidden from the outside world.

NAT isn’t about automatically assigning IPs (that’s DHCP), nor does it encrypt traffic (encryption is a separate process or protocol), and it isn’t primarily a traffic filter (that’s the job of a firewall or ACL). The core purpose is address translation, which is why translating a private IP to a public IP and back is the best description.