In .NET by assembly versoning allows the application to include an version of the library it needs to run. (Dll problem in Win32 is to identifying the correct library which not includes version)

DLL hell is Nothing but it is Vesioning Probles, This Problem can solved by Using Side by side Excution.
DLL hell is Multiple vesions of Applications not running Under one Assembly,By usingSide by Side Excutions .

The DLL Hell problem is solved in .NET by the introduction of the versioning of class libraries. Also by the advent of the CLR (common language runtime) which has most of the classes in it.