What is network access control and what does it check?

Network access control, or NAC, evaluates devices attempting to connect to the network and enforces security policies before granting access. NAC typically checks whether the device has current antivirus definitions, operating system patches, an active firewall, disk encryption enabled, and compliant configuration settings. Devices that pass the health check receive full network access. Devices that fail are placed in a quarantine network with limited access to remediation resources where they can update to compliance.