What is the role of backbone routers in relation to private IP addresses?

• A. They translate internal IP addresses to public addresses.
• B. They route all traffic through a DMZ.
• C. They do not allow packets from or to internal IP addresses.
• D. They block all external traffic.

Answer: (C)

Backbone routers sit in the core of the Internet and move traffic between networks using globally routable, public IP addresses. Private IP addresses (like those from 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16) are not routable on the public Internet, so they aren’t forwarded across the backbone to other networks. Instead, traffic from a private network must be translated to a public address at the network edge (via NAT or similar mechanisms) before it can traverse the backbone. That’s why private addresses don’t pass through the core routers to reach external networks. The other concepts—translating internal to public addresses, routing through a DMZ, or blocking all external traffic—are handled by edge devices, security architectures, or firewall policies, not by the backbone itself.