* [root@node1 ~]# nmcli connection show
[root@node1 ~]# nmcli connection add con-name static ifname enp1s0 type ethernet ipv4.addresses 172.25.15.10/24 ipv4.gateway 172.25.15.2 ipv4.dns 172.25.15.2
[root@node1 ~]# nmcli connection modify static ipv4.method manual connection.autoconnect yes
[root@node1 ~]# nmcli connection modify static +ipv4.addresses 10.0.0.5/24
[root@node1 ~]# nmcli connection up static
[root@node1 ~]# nmcli connection show
[root@node1 ~]# hostnamectl set-hostname node1.domain15.example.com
[root@node1 ~]# hostnamectl status
[root@node1 ~]# nmcli connection down static
* [root@node1 ~]# nmcli connection up static
[root@node1 ~]# ip addr show
[root@node1 ~]# reboot
### For checking ###
[root@node1 ~]# ip addr show
[root@node1 ~]# netstat -nr
[root@node1 ~]# cat /etc/resolv.conf

Answer see in the explanation.
Explanation/Reference:
# fdisk /dev/vda
n
+512M
w
# partprobe /dev/vda
# mkfs -t ext4 /dev/vda5
# mkdir -p /data
# vim /etc/fstab
/dev/vda5 /data ext4 defaults 0 0
# mount -a

see explanation below.
Explanation
/etc/init.d/iptables start
iptables -F
iptables -X
iptables -Z
/etc/init.d/iptables save
chkconfig iptables on

Yum-config-manager --add-repo=http://content.example.com/rhel7.0/x86-64/dvd" is to generate a file vim content.example.com_rhel7.0_x86_64_dvd.repo, Add a line gpgcheck=0 Yumcleanall Yumrepolist Almost 4305 packages are right, Wrong Yum Configuration will lead to some following questions cannot be worked out.

vim /etc/sysctl.conf net.ipv4.ip_forward = 1
sysctl -w (takes effect immediately)
If no "sysctl.conf" option, use these commands:
sysctl -a |grep net.ipv4
sysctl -P net.ipv4.ip_forward = 1
sysctl -w