During a port scan, Maria discovers a system running services on TCP and UDP 137–139 and TCP 445, as well as TCP 1433. What type of system is she likely to find if she connects to the machine?

TCP and UDP ports 137–139 are used for NetBIOS services, whereas 445 is used for Active Directory. TCP 1433 is the default port for Microsoft SQL, indicating that this is probably a Windows server providing SQL services.