Separates privilege granting software from authentication software sys admin can decide what auth scheme to use for each application PAM config file format      

/etc/dhcp.conf      dhcpd it is daemon name specify range of IP address specify lease duration can assign fixed addresses  

Network Information Service. The Network Information Service (NIS) provides a simple network lookup service consisting of databases and processes. It was formerly known as Sun Yellow Pages (YP). The functionality of the two remains the same; only the name has changed. Its purpose is to provide information, that has to be known throughout the network,  Full Article…