I want to communicate with Raspberry pi sensor node connected to DHCP network. As node has dynamically allotted ip, I cant directly communicate from with it. How can I do that?
You'll need a zero configuration alternative to deal with returning your changing ip for a given name. On other operating systems the bonjour service deals with this. On raspian you can install avahi:
sudo apt-get install avahi-daemon avahi-browse
This should make your pi available on the network as raspberrypi.local, unless you changed the hostname to something else in the raspian configuration. Avahi browse is optional, but handy to list the names of devices on your network