Downstream NTP servers in the hierarchy derive their clock from servers  ______________________

Downstream NTP (Network Time Protocol) servers in the hierarchy derive their clock from servers that are located at higher levels in the NTP hierarchy, which are referred to as upstream servers. Typically, this hierarchy is structured in a tiered manner, where the topmost servers (stratum 0) are directly connected to an accurate time source, such as a GPS or atomic clock. Stratum 1 servers are those that are directly synchronized to these stratum 0 devices and serve as the primary reference for lower stratum servers.

So, downstream NTP servers receive their time data from these upstream servers, which help maintain accurate time across various devices in a network. This method of operation allows for a distributed and hierarchical time synchronization architecture to ensure that timekeeping remains precise and reliable across all connected systems.