Windows (NTLM) AuthenticationConnection Pooling in ADO.NET

The DataDirect ADO.NET data provider for Microsoft SQL Server supports Integrated Windows (NTLM) authentication. If the connection string used by a DbConnection object sets both the Integrated Security and Pooling connection options to true, the Domain and User ID information is included with the connection pooling qualification information. In this case, a unique connection string is not the only requirement for creating a pool - instead, a pool is created for each connection string passed by a particular user. This prevents impersonation of one SQL Server user by another through the connection pool.

Because new connection pools are created for each user who connects, consider carefully the values that you assign for the Min Pool Size and Load Balance Timeout connection string options. For example, suppose you have defined a minimum of 100 connections in each pool with a connection lifetime of 60 seconds for each connection. If you have 200 individual users connecting, system resources would be tied up.