Final answer:
The subject is Computers and Technology, specifically network and service discovery.
Step-by-step explanation:
The subject of this question is Computers and Technology. Specifically, it is addressing the concept of network and service discovery.
Network and service discovery involves the process of identifying hardware and software Configuration Items (CIs) in a network and adding them to the Configuration Management Database (CMDB). In this case, it is mentioned that something crawls through the network and services to identify these CIs.
Examples of tools that perform network and service discovery include network scanning tools like Nmap and Zenmap which scan IP addresses and network services to provide information about the devices and services available on a network.