Hi,

This is part third of .Net interview questions. We are covering WCF interview  questions in this blog, so without wasting time lets start:

Default question: (for each question from below list, prepare examples from your latest projects. Because there is always a default question with each question

("Where did you use it in your latest project and why?"). By giving examples form your current projects will make an impression in interviewer's mind that you are not just read it up but you are in practice to follow good coding standards.

1. How do you rate yourself in WCF service out of 5.
2. What is WCF service and what is the advantage of this over web service(.asmx) ?
3. What is the base class of WCF service ?
4. What are the advantages and disadvantages of WCF service?
5. What are the end points of WCF services?
6. How do you decide when should we create WCF service and when MVC Web API? What are the differences between them ?
7. What is REST api?
8. What are service contracts and operation contracts?
9. How a service implements different service contracts and how to configure different end point for them?
10. How to make changes to WCF service without breaking the existing clients?
11. What are data contracts and data members in WCF service?
12. What is KnownType attribute in WCF service? what are the different ways to associate known type over service contract?
13. How do you enable massage logging and tracing in WCF service?
14. What is message contract in WCF and what is it's the advantages over data contract?
15. How to make changes in WCF contract in backward compatible manner so it doesn't break the existing clients?
16. What is the use of extension data object in WCF or What is the DataExtensibleDataObject interface?
17. What is the risk of implementing IDataExtensibleDataObject interface?
18. How do you handle exceptions in WCF service?
19. What is SOAP fault in WCF?
20. How to manage unhandled exception in WCF service?
21. How do you throw fault exception from WCF service?
22. How do you create strongly typed SOAP fault in WCF?
23. How do you implement centralized exception handling in WCF serice?
24. What are the different kinds of binding in WCF service?
25. How do you configure end points dynamically from code behind ?
26. How many ways you can host a WCF service? What is self hosting?
27. How to host a wcf service over window service and IIS?
28. Advantages and disadvantages of hosting wcf service over IIS?
29. What is WAS hosting in wcf?
30. What are the different message exchange patterns in WCF?
31. How do you implement Duplex message exchange pattern ?
32. What is default message encoding mechanism in wcf and what are the advantages and disadvantage of it?
33. What are the other ways to send large binary messages in wcf? Or what is MTOM ?
34. What are the instancing modes in wcf and how to define it? or what are the difference between PerCall, PerSession and Single instancing modes in wcf?
35. How to retrieve session id wcf service and client?
36. What is single instance context mode in wcf service?
37. What is session mode enumeration in wcf service?
38. What is single concurrency mode in wcf?
39. what is multiple concurrency mode in wcf?
40. What is reentrant concurrency mode in wcf?
41. What is throttling in wcf service ?
42. What is wcf security? What is transport security and message security ? How do you achieve this in wcf?
43. How do you control wcf message protection using protection level parameter?
44. What default security wsHttpBinding, basicHttpBinding, netTcpBinding support ? and how to configure wsHttpBinding to support transport level security?
45. How do you achieve authentication and authorization in wcf service?
46. What is message confidentiality and integrity with transport security ?
47. How do you configure netTcpBinding to use message security?
48. How do you configure SSL in wcf service? 
49. How do you configure 2 way or mutual SSL ?
50. To build communication on 2 way SSL what are the handshaking messages between client and server processed? or how communication happen between client and server using 2 way SSL or mutual SSL authentication ?