Update DNS Server Information on Linux CentOS 7

To update the DNS server that the operating system will refer to, please follow below easy steps

1. Edit /etc/resolv.conf. In this example I use nano text editor. If you do not have nano, you can install it by running "yum install nano -y"
# nano /etc/resolv.conf

2. Type in "nameserver" followed by a space, and followed by your DNS server ip address. Please remember that the sequence of the entry is important. So please put your primary DNS server on top of your secondary server in the /etc/resolv.conf. In this example, my primary DNS is 192.168.1.1 and my secondary DNS is 192.168.1.2
nameserver 192.168.1.1
nameserver 192.168.1.2

3. Save and exit. For nano, you can simply press Ctrl-x, y and Enter.

4. Check if you have added the configuration correctly
# cat /etc/resolv.conf
nameserver 192.168.1.1
nameserver 192.168.1.2