What are private IP addresses?

• A. IP addresses that are routable on the public internet.
• B. IP addresses that are not routable on the public internet.
• C. IP addresses assigned to servers by ISPs.
• D. IP addresses reserved for testing.

Answer: (B)

Private IP addresses are the addresses used inside local networks and are not meant to be reachable from the public Internet. They let devices on a home or corporate LAN talk to each other using addresses like 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Because they aren’t routable on the wider Internet, routers on the Internet won’t forward packets with these addresses; instead, a network device such as a router translates outbound traffic to a public IP via NAT so responses come back correctly. This is different from public IP addresses, which are assigned by ISPs and are globally routable. Private addresses can be reused in different networks without conflict. The idea of addresses reserved for testing points to separate, special-purpose blocks, not the private ranges used inside networks.