How to update/edit a static IP address on CentOS 7 / RHEL 7

How do I list network interfaces?

Type the following command:
# ip a

Fig.01: List NICs in a CentOS 7 server using ip commandOr use the following command:
# nmcli -p dev
Sample outputs:

Fig.02: nmcli command in actionHere is a typical DHCP configration for eth0 (stored in /etc/sysconfig/network-scripts/ifcfg-eth0 file):

DEVICE="eth0"
ONBOOT=yes
NETBOOT=yes
UUID="41171a6f-bce1-44de-8a6e-cf5e782f8bd6"
IPV6INIT=yes
BOOTPROTO=dhcp
HWADDR="00:08:a2:0a:ba:b8"
TYPE=Ethernet
NAME="eth0"

How do I configure an eth0 interface with static network IP settings (method # 1)?

To configure an eth0 interface with static network settings using ifcfg files, edit or create a file with name ifcfg-eth0 in the /etc/sysconfig/network-scripts/ directory as follows:
# vi /etc/sysconfig/network-scripts/ifcfg-eth0
Update/edit as follows for static IP configuration:

# static IP address on CentOS 7 or RHEL 7#
HWADDR=00:08:A2:0A:BA:B8
TYPE=Ethernet
BOOTPROTO=none
# Server IP #
IPADDR=192.168.2.203
# Subnet #
PREFIX=24
# Set default gateway IP #
GATEWAY=192.168.2.254
# Set dns servers #
DNS1=192.168.2.254
DNS2=8.8.8.8
DNS3=8.8.4.4
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
# Disable ipv6 #
IPV6INIT=no
NAME=eth0
# This is system specific and can be created using 'uuidgen eth0' command #
UUID=41171a6f-bce1-44de-8a6e-cf5e782f8bd6
DEVICE=eth0
ONBOOT=yes

Save and close the file. You do not need to specify the network or broadcast address as this is calculated automatically by the system. To restart networking service, enter:
# systemctl restart network

Verification

Verify new IP settings:
# ip a s eth0
Verify new routing settings:
# ip r
Verify DNS servers settings:
# cat /etc/resolv.conf
Verify the internet connectivity:
# ping -c 3 cyberciti.biz
# ping -c 4 google.com
Sample session:

Fig.03: Testing networking and make sure everything is working

How do I configure an eth0 interface with static IP address on CentOS 7 / RHEL 7 using Network Manager (method # 2)?

You need to use the nmtui command. It is a curses?based TUI application for interacting with NetworkManager. To show a connection editor that supports adding, modifying, viewing and deleting connections. To view or setup a static IP using this tool for eth0, enter:
# nmtui edit eth0
Sample outputs:

Fig.04: nmtui is a curses?based TUI application for interacting with NetworkManager.