IP address renewal

1. Find the interface (e.g. eth0, eth1, enp1s0, sit0, wlan0, ...):

   $ ip addr

2. Release its IP:

   $ dhclient -r <interface>

3. Request new IP from DHCP server (alert on error):

   $ dhclient -1 <interface>

4. Check its new IP:

   $ ip addr

SEE: Serverfault.com

NOTE: Confirmed on: Debian 9.3 (Stretch) and Ubuntu 16.04 LTS!