Your question is Explain Networking Fundamentals: Subnet Masks, VPNs, DHCP, and IPs. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain how subnet masks, VPNs, DHCP, and IP addresses function in a network environment and how you troubleshoot related issues.