The customer wished to install/remove/upgrade the .NET frameworks on their server and want to know if this will impact their DLP installation.
No it will not, as of DLP 15.8 DLP does not have any dependencies on the .NET framework and the customer is free to install/uninstall/upgrade .NET as needed.
.NET35 was used in DLP 15.7 and earlier for the SOAP API, this is now deprecated and no longer used in current releases.