SQL Server 64 bit clients

An interesting topic/discussion i came across today is connecting to SQL Server 2005 64 bit server from 64 bit clients. What options does one have?

 There are several good references out there. The best one i could find on this was the Data Access roadmap article here: https://msdn2.microsoft.com/en-us/library/ms810810.aspx

Essentially, there are 2 main options:

1) Connecting from 64 bit native applications: 

There are two further choices here: 

a) Use MDAC that ships with the OS: 64 bit drivers ships with the OS. This cannot take advantage of the new features in SQL 2005 like database mirroring for example but works well with existing applications that do not need that.

 or

b) Use SQL Native Client that ship with SQL Server 2005: This will need to be used to take advantage of new SQL 2005 features. This combines ODBC and OLEDB into a single DLL.

2) Connecting from 64 bit Managed applications:

Use ADO.NET

The other frequently asked question is if you can access 64 bit SQL Server from a 32 bit clients without making any modifications to the app - The answer is YES!