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 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. Each cache has a separate TTL (time-to-live) for its data; modifying the local database (/etc/passwd, and so forth) causes the cache to become invalidated within fifteen seconds. Note that the shadow file is specifically not cached. getspnam(3) calls remain uncached as a result.