If you need to change centos 6 ip or gateway and also dns configurations you can use this post .
IP and Gateway configuration
With this 2 commands you can see centos network configurations
nano /etc/sysconfig/network-scripts/ifcfg-eth0
vi /etc/sysconfig/network-scripts/ifcfg-eth0
the result of this commands should be sommthing like this
DEVICE=eth0
TYPE=Ethernet
UUID=281a600c-aaba-4297-bf51-15b18d2d8619
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=none
IPADDR=23.227.x.x
PREFIX=26
GATEWAY=23.227.x.x
DNS1=4.2.2.4
DOMAIN=8.8.8.8
DEFROUTE=yes
IPV4_FAILURE_FATAL=yes
IPV6INIT=no
NAME="System eth0"
HWADDR=00:50:56:B0:4D:D6
LAST_CONNECT=1410687738
2 important element that you should change are IPADDR & GATEWAY
to change the ip address change the value of IPADDR and to change gateway change the value of GATEWAY
Gateway Configuration
With this 2 commands you can see centos Gateway configurations
nano /etc/sysconfig/network
vi /etc/sysconfig/network
the result of this commands should be sommthing like this
NETWORKING=yes
HOSTNAME=server.domain.com
GATEWAY=23.227.x.x
you can change the Gateway by editing the value of GATEWAY
Configure DNS Server
With this 2 commands you can see centos Gateway configurations
nano /etc/resolv.conf
vi /etc/resolv.conf
the result of this commands should be sommthing like this
nameserver 8.8.8.8
nameserver 192.168.1.1
you can change the values for dns servers
For learning Nano editor click link below
http://monovm.com/post/35/Nano-Editor-Learn
Regards
MonoVM.com