Hi Suresh,
I too posted a similar question last week but as yet I haven't had any replies.
From what I have read on this site and others, it seems that you only need to be aware of what a socket is (a connection between two machines) and that they have an InputStream and an OutputStream.
I would imagine any question about sockets would be about reading from and/or writing to a socket. I don't think you have to have an indepth knowledge.
Sockets are mentioned in RHE so it's worth reading that, otherwise read the Sun API docs.
I'm taking the exam in just over a week so if anyone does know the answer, please reply to this
thread or to my earlier thread
http://www.javaranch.com/ubb/Forum24/HTML/003056.html. Lee.