NAT hairpinning (NAT loopback) allows internal clients to access an internal resource using which addressing method from inside the network?

• A. Accessing an internal resource using its public IP address from inside the network.
• B. Accessing an internal resource using a private IP address from outside the network.
• C. Using a VPN tunnel to reach internal resources.
• D. Blocking inbound connections to internal resources behind NAT.

Answer: (A)

NAT loopback lets internal clients reach an internal resource by using the public IP address of that resource from inside the network. When an internal computer targets the public IP, the NAT device recognizes the mapping and rewrites the destination to the internal private IP of the resource, routing the traffic back inside the local network. This lets internal users access internal services as if they were reached from outside, using the external address.

So the correct description is: accessing an internal resource using its public IP address from inside the network. The other options describe different mechanisms or misapply the concept: using a private IP from outside is not hairpinning, a VPN tunnel is a separate remote-access method, and blocking inbound connections isn’t about reaching internal resources.