[root@localhost ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0 

DEVICE="eth0"
BOOTPROTO=none
BROADCAST="172.255.255.255"
NETMASK="255.0.0.0"
IPADDR="172.31.255.126"
IPV6INIT="yes"
NM_CONTROLLED="yes"
ONBOOT="yes"
TYPE="Ethernet"
UUID="f83e465e-dbdb-4843-99c5-199783e89e99"
HWADDR=00:0C:29:6C:40:1B
PREFIX=8
GATEWAY=172.31.255.177
DNS1=211.157.15.189
DOMAIN=172.31.255.177
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
IPV6_FAILURE_FATAL=no
NAME="System eth0"
LAST_CONNECT=1496195215

:wq

[root@localhost ~]# /etc/init.d/network restart

ok