Here I am going to give Number of Questions which not only raise your interest in IIB as well as How You  come up with those question being asked in interview .........It will go likewise 

WMB IIB Interview Questions for

1. Brief Introduction

 They are expecting detailed introduction like the nodes used etc.

2.Diffrence and usage of XMLNSC and XMLNS domains

3. Imagine the input is 3000 bytes long and CWF format. inside which an xml is coming,  How do you access 5th field in XML.

4. Difference between Database and Compute node  and steps in accessing a DB. 

5. Trace commands

6. Imagine 3000 messages are coming to the flow at a given interval and your flow is capable of handling 1000 messages, how do you increase message thruput.

We can deploy additional instances to increase thruput, and then maximum instances allowed is 256.

7. How do access second last child element in the xml.

8. If you are assigning InputRoot to OutputRoot ,where as the inputrootreferance is null, what will happen?

9. When you have a field and its attribute with the same, the target should require only the attribute value, how do you access it?

they mean to say for eg:  < Folder1 Item ='ABCDE'>

                        <Item> 12345 </Item>

                  </Folder1>

Inorder to access Attribute you should specify as

      SET AttrValue = InputRooot.XMLNSC.Folder1.(XMLNSC.Attribute) Item ;

10. How do you make a variable available across\multiple messages,.

      Variable scoping, use external variable, which will be available across messages and to the entire life of the flow.