etcnscdconf

etcnscdconf is the configuration file used by the Name Service Cache Daemon (nscd) on many Unix-like systems. The file governs how the daemon caches results of Name Service Switch (NSS) lookups, such as user accounts, groups, host names, and network services, to speed up repeated queries. By controlling caching behavior, etcnscdconf helps reduce load on external sources like files, LDAP, or DNS while improving system performance.

Location and purpose: The file is typically /etc/nscd.conf. nscd reads this file at startup and when signaled to reload. The daemon caches data for NSS databases including passwd, group, hosts, services, and netgroup. Caching accelerates common lookups such as login, su, and hostname resolution, but introduces a small window where changes on the source side may not be immediately visible.

Configuration options: The file uses per-database directives to enable or disable caching and to set time-to-live values for cached entries. Common options include enable-cache for each database, positive-time-to-live and negative-time-to-live to control how long positive results and negative results are cached, and suggested-size to influence cache allocation. Additional directives may configure logging (logfile) and debugging (debug-level). The exact syntax can vary by version.

Examples: enable-cache passwd yes; enable-cache hosts yes; positive-time-to-live passwd 600; negative-time-to-live passwd 20; suggested-size passwd 1000. After editing, apply changes by reloading or restarting nscd (for example, systemctl reload nscd or systemctl restart nscd).

Notes: Changes affect all users and processes. In environments using alternative services (sssd, unscd), nscd may be unused. Always refer to the local man page (nscd.conf) for version-specific directives and defaults.