For implementations that cache, the expiration age is the maximum amount of time, in seconds, that a cached copy of data from a name service attribute is considered valid by name service operations that read data from a name service. When there is no cached copy, the operation creates one with fresh data from the name service database. When there is a cached copy, the operation compares its age with the calling application's expiration age. If the copy's age exceeds the expiration age, the operation attempts to update the cached copy with fresh data from the name service. Fresh data is always retrieved from the name service.
Every application maintains a global expiration age value.
Applications may also set the expiration ages of individual name service handles. Whenever a name service operation is performed using a handle for which the application has not set an expiration age, the global expiration age value is used. Permissions Required None. Please note that the html version of this specification may contain formatting aberrations. The definitive version is available as an electronic publication on CD-ROM from The Open Group.