After you have installed NIS, you might discover that some maps require frequent updating while others never need to change. For example, the passwd.byname map can change frequently on a large company's network, while the auto_master map changes little, if at all.
As mentioned in Default NIS Maps, the default location of the default NIS maps is on the master server in /var/yp/domainname, where domainname is the name of the NIS domain. When you need to update a map, you can use one of two updating procedures, depending on whether or not it is a default map.
Maps that are included with an application purchased from a vendor
Maps that are created specifically for your site
Maps that are created from a non-text file
The following sections explain how to use various updating tools. In practice, you might decide to only use them if you add non-default maps or change the set of NIS servers after the system is already up and running.