Q1: Say for 2 nodes cluster, Do we need to have 2 copies of Databases( 1 on each node).
Ans: Because in a clustering environment normally sql database hosted only SAN(single point of database copy only).
Q2:Hows does the data Synchronization between different nodes of databases takes place?
Ans: Sql server 2000/2005/2008-environment, sql server having own quorum mechanism, we need to select the quorum model and MSdtc .
Q3:In Active/Passive mode, does the passive node database is exactly in the same state (in terms of data) as that of Active?
Ans: yes--Because if something happened the active node all the sql resource has moved to passive node with in 15 secs. so that data has same state.