Network Access Protection (NAP) is a platform that network administrators can use to help protect the security of a network. When you connect to a corporate network that uses NAP, your computer is checked to make sure that it has the required software and settings, and that the software and settings are up to date. If anything is missing or outdated, your computer can be automatically updated. Your network access might be limited during that time, but usually this process happens quickly, after which full network access is restored. So it checks if the computer you are connecting over network is really safe to connect or not. If any violation to NAP protocols is there such as presence of Virus, Trojans etc. over the network computer you are connecting NAP won‟t allow you to connect. Enabling NAP enhances your security over network and you will be much safer.
You can see if it is Activated here: Control Panel >System Security>Action
Center>NAP Status On/Off