[CentOS] why would ls, while or ci use NIS?

Wed Jun 21 20:27:58 UTC 2017
Gordon Messmer <gordon.messmer at gmail.com>

If you have NIS configured, it'll be used by anything that needs to map 
a uid or gid number to a name, or anything that needs a list of groups 
for users, among other things.

That means (IIRC) that having a crontab implies a NIS lookup, because 
creating a new session for your user needs to fetch supplementary groups 
from NIS (even for root).

'ls -l' might also do lookups to resolve the uid/gid of your local 
files.  "local files" does not imply that there is no need for YP.