When performing a recon on a network, whether wireless or LAN based, you may come across devices identified by its MAC address. To get a better footprint of the environment, it is definitely useful to determine the type of device riding within the enterprise. This can usually be done by an nmap sweep of the local environment. Once MAC addresses are gathered, the vendor of the unknown device can be concluded by visiting the following:
https://standards.ieee.org/develop/regauth/oui/oui.txt.
The first three octets are usually reserved by the vendor.