Final answer:
The administrator used passive fingerprinting in this penetration test scenario by connecting a notebook system to a mirror port on a network switch and using a packet sniffer to monitor network traffic.
Step-by-step explanation:
The process the administrator used in this penetration test scenario is passive fingerprinting.
Passive fingerprinting involves monitoring network traffic without actively engaging with the network hosts. By connecting a notebook system to a mirror port on a network switch and using a packet sniffer, the administrator can passively observe the network traffic and analyze the packets to determine which operating systems are running on the network hosts.