CCNA Routing and Switching (legacy) — Question 155

What will happen if a private IP address is assigned to a public interface connected to an ISP?

Answer options

• A. A conflict of IP addresses happens, because other public routers can use the same range.
• B. Addresses in a private range will not be routed on the Internet backbone.
• C. Only the ISP router will have the capability to access the public network.
• D. The NAT process will be used to translate this address to a valid IP address.

Correct answer: B

Explanation

The correct answer is B because private IP addresses are not routable on the public Internet, meaning they cannot be used for communication over the Internet backbone. Option A is incorrect as a conflict does not occur at the ISP level due to the private nature of the address. Option C is misleading because, while the ISP router can access the public network, it does not imply that only it can do so. Option D is incorrect as NAT typically translates private addresses to public ones, not the other way around.