# service nscd restart
Usually you do not need to modify the /etc/nscd.conf and the current default should suffice for most situation.
According to Linux Manual Page
Nscd is a daemon that provides a cache for the most common name service requests. The default configuration file, /etc/nscd.conf, determines the behavior of the cache daemon. See nscd.conf(5).
Nscd provides cacheing for accesses of the passwd(5), group(5), and hosts(5) databases through standard libc interfaces, such as getpwnam(3), getpwuid(3), getgrnam(3), getgrgid(3), gethostbyname(3), and others.......