Rama,
The
SCJP objectives state the following.
State the benefits of encapsulation in object oriented design and write code that implements tightly encapsulated classes and the relationships "is a" and "has a".
On the real exam, I recall there were questions that implement "is-a" and "has-a" relationships and the questions ask which relationships are examples of "is-a" and which are examples of "has-a". I don't recall any questions that were designed to determine if you really understand the appropriate use of each kind of relationship. I suppose that concept may have been deferred to the developer exam.
From my point of view, if you're going to
test if a person is able to recognize a relationship, then it makes sense to determine if the person has a basic understanding of the appropriate use of the relationship. If the usage of the relationships is not understood, then what is gained by recognizing the relationships?
This question might be slightly beyond the scope of what is likely to appear on the real exam, but it certainly is not beyond the scope of what every employer will expect each programmer to understand.