Overview#NSCD, Name Service Cache Daemon, is a daemon that provides a cache for the most common Name Service Switch requests. The default configuration file, /etc/nscd.conf, determines the behavior of the cache daemon.
NSCD provides caching 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.
There are two caches for each database: a positive one for items found, and a negative one for items not found. Each cache has a separate TTL (time-to-live) period for its data. Note that the shadow file is specifically not cached. getspnam(3) calls remain uncached as a result.