Adding second ip address Ubuntu 16.04

How do I add a second IP address to a Ubuntu 16.04 machine?

So far, I did the following:

1. Opened /etc/network/interfaces/
2. Added the following lines
iface eth0 inet static
address X.X.X.X
netmask 255.255.255.0

when I ping the new IP from the same computer, it responds to ping, but when I ping it from a different PC it says DESTINATION HOST UNREACHABLE

Any idea ?

 

same network controler
iface eth0:1 inet static
address X.X.X.X
netmask 255.255.255.0

diffrent network controller
iface eth1 inet static
address X.X.X.X
netmask 255.255.255.0

you have to start/restart the second network interface

 

Yes, I did that and still the second IP doesn't work.