If I use Dynamic DNS such as the free service at https://www.dyndns.com, do I still need to set up static IP and do port forward ?
I have a DSL, most likely with dynamic IP address, and I run a Java servlet to get Paypal IPN messages on my notebook, in order for the messages to reach my notebook, I :
 set up static IP and  did port forwarding.
But I found each time the PC re-starts, it has a different external IP, so I was suggested to
 get Dynamic DNS service
like the free one mentioned above, but now I'm a bit confused, if I have step , do I still need to do  and , isn't step  supposed to do  and  for me ? But since I've already done ,, now I wonder if they would cause trouble for step , do I need to undo them ? Or do I need all of them together ?