nischttl changes the time to live value (ttl) of the NIS+ objects or entries specified by name
to time. Entries are specified using indexed names (see nismatch(1)).
The time to live value is used by object caches to expire objects within their cache. When an object is read into the cache, this value is added to the current time in seconds yielding the time when the cached object would expire. The object may be returned from the cache until the current time
is earlier than the calculated expiration time. When the expiration time has been reached, the object will be flushed from the cache.
The time to live time may be specified in seconds or in days, hours, minutes, seconds format. The latter format uses a suffix letter of d, h, m, or s to identify the units of time. See the examples
below for usage.
The command will fail if the master NIS+ server is not running.
Setting a high ttl value allows objects to stay persistent in caches for a longer period of time and can improve performance. However, when an object changes, in the worst case, the number of seconds in this attribute must pass before that change is visible to all clients. Setting
a ttl value of 0 means that the object should not be cached at all.
A high ttl value is a week, a low value is less than a minute. Password entries should have ttl values of about 12 hours (easily allows one password change per day), entries in the RPC table can have ttl values of several weeks (this information
is effectively unchanging).
Only directory and group objects are cached in this implementation.