To specify the new domain name server, you will need to edit the file resolv.conf. Open the file with any text editor:

nano /etc/resolv.conf  

and replace the ip-address with a new one in the line nameserver:

# Generated by NetworkManager
search fornex.cloud  
nameserver 91.228.153.88  
nameserver 212.224.118.111  

Also, to keep your settings intact after a reboot, you will need to make changes to the network interface configuration file:

nano /etc/sysconfig/network-scripts/ifcfg-eth0  

Enter the new ip on the lines:

DNS1=91.228.153.88  
DNS2=212.224.118.111