By Default Ubuntu uses DHCP settings to attain an IP Address for the system. However in many cases you may need to use a static IP address , if your Ubuntu system is using DHCP and you want to assign it a Static IP address then its not a big deal to configure it. Simply go through the following easy steps to achieve it.
First of all, right click the network icon located in the top panel and select Edit Connections.
The Network Connection window will be displayed, now click the Add button to add a new network connection, and then go directly to the IPV4 settings tab.
Choose the Manual option from the Method drop down menu.
Now click Add and then enter the IP address, Netmask and Gateway information in the Addresses section.
Click the Apply button to complete the configuration. Now you can use this newly created network connection which will have a static IP address. Enjoy!