Ubuntu:Resolve Sudo Name Resolution

• Check in your hostname by running the command "hostname" on your terminal. The result will be blank as there is no hostname assigned.
• Edit the /etc/hostname file in which the hostname is stored in your system. Provide any hostname of your choice. As an example, I have assigned the hostname as inspiron-3558. You can use the following command to edit the file.

nano /etc/hostname

Note: You will need root permission to edit the file

• Once you have saved the file with your new hostname, run the command "hostname" to confirm. The new hostname should be displayed on the screen.
• Check the /etc/hosts file and edit the hostname same as in /etc/hostname. The hosts file maps the hostname to IP addresses. Hence, it is very important that you edit the hostname in the file. Please edit the hostname mapped with the IP address

127.0.1.1 

• Any changes made in the files do not take effect until the system is rebooted. So, please reboot the system for the changes to take effect.
• After rebooting check the sudo command to ensure it is working properly.

Source

• psychz.net