A rights validator system for controlling access to content, the system including a query processor to receive a rights query and to provide a result to the rights query based on an estimated time, and a time-based query response module operationally connected to the query processor, the time-based query response module being operative to determine the estimated time as a function of a most recently updated time, and a plurality of indications of elapsed time since the most recently updated time, the indications of elapsed time being from a plurality of different sources of time indication. Related apparatus and methods are also included.