Exchange 2010 and Windows Server 2008 SP2 operating system prerequisites
In order to install Exchange 2010 there are various prerequisites that are required. One of those is .NET Framework 3.5 SP 1, If you try and install the dotnetfx35Setup file you’ll get the following error:-
What you’ll need to do is install .NET framework using the Add Features Wizard as shown below:-
Then you can carry with the installation of Exchange 2010 (providing you have completed the remaining requirements - https://technet.microsoft.com/en-us/library/bb691354.aspx)
Written by Daniel Kenyon-Smith