What is the difference between private and public IP addresses and why NAT is used?

What is the difference between private and public IP addresses and why NAT is used?

• A. Private addresses (RFC1918) are non-routable on the Internet; public addresses are globally routable; NAT maps multiple device addresses to a public IP, enabling Internet access.
• B. Private addresses are globally routable; public addresses are not.
• C. NAT assigns unique public addresses to each device.
• D. Public addresses are used for private networks only.

Answer: (A)