Hi Rupesh,

Stratum is used to define the distance from the reference clock. Reference clock is typically a stratum 0 device (assumed to be accurate with lttle or no delay associated with it).

Thus the server which is directly linked to a stratum 0 server is called a stratum 1 server and a server. Statum 2 server will be a server connected to stratum 1 server over network and so on.

Have a look at this link from Wiki -

http://en.wikipedia.org/wiki/Network_Time_Protocol#Clock_strata

-> Sushil