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.
file is specifically not cached. getspnam(3) calls remain uncached as a result.
Some Redhat systems maybe using SSSD
instead of NSCD.
NSCD doesn't know anything about the underlying protocols
for a service. This also means, that if you change /etc/resolv.conf for DNS
queries, nscd will continue to use the old one if you have configured /etc/nsswitch.conf to use DNS
for host lookups. In such a case, you need to restart NSCD.
There might be more information for this subject on one of the following: