If you are interviewing for a Job in .NET, here are some common questions
1) What is the difference between Abstract Classes and Interfaces
2) What do you know of Heaps and Stacks
3) Explain Polymorphism, Inheritance, Encapsulation
4) What is a delegate and how do you use it?
5) Describe the .NET Framework.
6) List the Page Events
7) What are the many ways you handle State in ASP.NET and explain each one

Tell us a big about what you know of the Garbage Collector
9) What is GAC?
10) What is the difference between a String and String builder??
11) What is Deadlock??
12) What are the differences between Structure and Classes??
13) What is an XML Schema??
14) What are the different class modifiers and explain each one of them
15) What is Assembly Manifest??
16) What is Threading??
18) Explain the role of the garbage collector?