You have set up a local area network for your company. Your firewall separates your network into several sections: a DMZ with semi-public servers (web, dns, email) and an intranet with private servers. A penetration tester gains access to both sections and installs sniffers in each. He is able to capture network traffic for all the devices in the private section but only for one device (the device with the sniffer) in the DMZ. What can be inferred about the design of the system?