Chord protocol - How should I go about mapping nodes to placeholders on the ring? In the real world, how is a node mapped to the position on the ring, 
Each nodes's IP address is hashed using SHA-1 hashing algorithm which will produce this hash - 73.128.154.69 hashed into 60CBFB98C9052A425D684A2C3D8D8D38424129A3. 
This should have been in the range of 0 to (2^m) - 1 where m is the number of bits. I have the following questions - 


How should I convert this hashed value into a number?
Will the IP address after leaving and re-joining the ring get the same  placeholder position?
Are placeholders or node positions ordered numbers at all?
Take the last m bits of the hash.  View it as a number in binary.  That's how you convert the hashed value into a number.  The position is a number.  That should answer your questions 1 &amp; 3.

Now that you know how it works, you should be able to answer question 2 yourself.  If not, go back and read the original paper (especially Section IV.B), which should make this clear.