SQL Server 2008

1. What are the basic functions for master, msdb, model, tempdb and resource databases?
   1. The master database holds information for all databases located on the SQL Server instance and is theglue that holds the engine together. Because SQL Server cannot start without a functioning masterdatabase, you must administer this database with care.
   2. The msdb database stores information regarding database backups, SQL Agent information, DTS packages, SQL Server jobs, and some replication information such as for log shipping.
   3. The tempdb holds temporary objects such as global and local temporary tables and stored procedures.
   4. The model is essentially a template database used in the creation of any new user database created in the instance.
   5. The resoure Database is a read-only database that contains all the system objects that are included with SQL Server. SQL Server system objects, such as sys.objects, are physically persisted in the Resource database, but they logically appear in the sys schema of every database. The Resource database does not contain user data or user metadata.
2. What is Service Broker?
   Service Broker is a message-queuing technology in SQL Server that allows developers to integrate SQL Server fully into distributed applications. Service Broker is feature which provides facility to SQL Server to send an asynchronous, transactional message. it allows a database to send a message to another database without waiting for the response, so the application will continue to function if the remote database is temporarily unavailable.
3. Where SQL server user names and passwords are stored in SQL server?
   They get stored in System Catalog Views sys.server_principals and sys.sql_logins.
4. What is Policy Management?
   Policy Management in SQL SERVER 2008 allows you to define and enforce policies for configuring and managing SQL Server across the enterprise. Policy-Based Management is configured in SQL Server Management Studio (SSMS). Navigate to the Object Explorer and expand the Management node and the Policy Management node; you will see the Policies, Conditions, and Facets nodes.
   
5. What is Replication and Database Mirroring?
   Database mirroring can be used with replication to provide availability for the publication database. Database mirroring involves two copies of a single database that typically reside on different computers. At any given time, only one copy of the database is currently available to clients which are known as the principal database. Updates made by clients to the principal database are applied on the other copy of the database, known as the mirror database. Mirroring involves applying the transaction log from every insertion, update, or deletion made on the principal database onto the mirror database.