SQL Server Optimization

What are the steps you will take, if you are tasked with securing an SQL Server?

Perform the following SQL checks after installing the Server:

• Check if Administrators group belongs to sysadmin role
• Check if CmdExec role is restricted to sysadmin only
• Check if SQL Server is running on a Domain Controller
• Check if sa account password is exposed
• Check SQL installation folders access permissions
• Check if Guest account has database access
• Check if the Everyone group has access to SQL registry keys
• Check if SQL service accounts are members of the local Administrators group
• Check if SQL accounts have blank or simple passwords
• Check for missing SQL hotfixes
• Check the SQL Server authentication mode type
• Check the number of sysadmin role members

Then, you should require Windows Authentication Mode for connections to SQL Server, whenever possible.

You should isolate your server and back it up regularly.

You should assign a strong sa password.

You should limit privilege level of SQL Server Services.

Configure your firewall to filter out packets addressed to TCP port 1433 and UDP port 1434. ports associated with named instances should also be blocked at the firewall.

You should Use a secure file system.

Old setup files should be Deleted or secured.

You should log failed connection attempts to SQL Server and review the log regularly.Enable auditing of failed connections with Enterprise Manager in SQL Server.

What is a deadlock and what is a live lock? How will you go about resolving deadlocks?

A deadlock can occur when two or more processes that strive to acquire resources are not able to acquire them due to some of the following reasons:

Two processes may be interdependent upon each other,

If there are more than 2 processes, then if a graph is plotted, then there could be a cycle,

A server maintains a graph. The processes acquiring the resources would intimate the server about their requirement. If the server detects an occurance of a deadlock, the user process is be terminated.

In a livelock, a request for an exclusive lock is denied repeatedly due to a series of overlapping shared locks that keep interfering.

An SQL Server detects this situation after four denials and then refuses further shared locks.

When a write transaction is forced to wait indefinitely due to read transactions that monopolize a table or a page then a live lock occurs.

Explain 'Hostprotectionattribute' in SQL server 2005.

It allows the use of declarative security actions to determine host protection requirements. This class cannot be inherited