Common steps
1) Update the machine and install necessary packages:
yum remove alsa* postfix
yum -y install wget libselinux-utils firewalld lsof vim nano net-tools
yum -y update
2) Disable network manager (we'll define networks manually):
systemctl stop NetworkManager
systemctl disable NetworkManager
3) Update resolv.conf:
# cat /etc/resolv.conf
nameserver 127.0.0.1
nameserver YOUR_SERVERS_IP
nameserver 8.8.8.8
4) Remove the ipv6 directives from ifcfg and setup a hostname
5) Disable SeLinux
setenforce 0
sed -i s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config
