In SQL Server 2005 while doing Replication (Snap Shot/ Transactional/ Marge Replication), what are the master tables are used ?
Replication in SQL Server 2005 is managed with reference to a group of system tables in the MSDB database, along with one in Master, and some tables in the Distribution, Publication and Subscription databases.
From http://msdn.microsoft.com/en-us/library/ms179855(SQL.90).aspx :
A replication topology is supported by replication system tables. When a user database is configured as a Publisher or a Subscriber, replication adds system tables to the database. These tables are removed when a user database is removed from a replication topology.
The Master table is used in snapshot replication and contains metadata about the replication, the current state of the snapshot, and rollback information in the event a transaction fails. Normally you can just forget about it, but in certain cases you can (very carefully) modify it directly, and save a lot of time instead of regenerating the snapshot.