How to connect raspberry pi with Ubuntu 14.04 using dynamic IP (via dhcp server) ?

Connect raspberrypi to Ubuntu 14.04. Assuming you have installed gnome-desktop.
Go to Wifi settings --> Wired connection --> look for IP address (if raspberrypi is connected to laptop with Patch cable and board is powered on)

install nmap in Ubuntu 14.04 using command $sudo apt-get install nmap

Use command on Ubuntu host $ sudo nmap -sP 10.42.0.2-255 (IP address 10.42.0.2 selected from the address retrieved from wired settings)

you may get message like

Starting Nmap 6.40 ( http://nmap.org ) at 2014-10-24 00:19 IST

Nmap scan report for 10.42.0.33

Host is up (0.00054s latency).

MAC Address: B8:27:EB:3E:64:DE (Raspberry Pi Foundation)

Nmap done: 253 IP addresses (1 host up) scanned in 22.15 seconds

 Now, dynamic IP address which is produced by dhcp server of raspbian OS is 10.42.0.33 (in this case)

now use terminal to ssh the raspberry pi using $pi@10.42.0.33
default password is : raspberry

Now, you should be able to access shell prompt of raspberry pi