Centos6.2 setting up static IP and DNS

Refer to the following articles:
https://gist.github.com/fernandoaleman/2172388
http://www.lifelinux.com/how-to-configure-static-ip-address-on-centos/
http://www.ehowstuff.com/how-to-configure-static-ip-address-on-centos-6-2-linux-server/
Http://www.liurongxing.com/centos-dns-ifcfg-resolv.html
http://bbs.csdn.net/topics/390162805
Http://www.cnblogs.com/shawnloong/archive/2011/11/23/2260757.html

1) at the beginning of the system is DHCP automatically obtain IP, look at the system's IP, similar to the following: (This step is more critical to find the corresponding network devices and configuration files)
[Email protected]_aaa ~]# ifconfig
Eth6 Link encap:ethernet HWaddr 08:00:27:c1:e4:3d
inet addr:192.168.0.103 bcast:192.168.0.255 mask:255.255.255.0
Inet6 ADDR:FE80::A00:27FF:FEC1:E43D/64 Scope:link
Up broadcast RUNNING multicast mtu:1500 metric:1
RX packets:108 errors:0 dropped:0 overruns:0 frame:0
TX packets:32 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:12689 (12.3 KiB) TX bytes:5908 (5.7 KiB)
Lo Link encap:local Loopback
inet addr:127.0.0.1 mask:255.0.0.0
Inet6 addr::: 1/128 scope:host
Up LOOPBACK RUNNING mtu:16436 metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:480 (480.0 b) TX bytes:480 (480.0 b)

2) Modify the corresponding/etc/sysconfig/network-scripts/ifcfg-eth6, but my following file does not exist, so directly create this file, the contents of the file is modified as follows:
Device=eth6
Hwaddr= "08:00:27:c1:e4:3d"
Nm_controlled=yes
Onboot=yes
Type=ethernet
ipaddr=192.168.0.120
Bootpro=static
netmask=255.255.255.0
dns1=192.168.0.1
Networking_ipv6=no
Ipv6init=no
Ipv6_autoconf=no
gateway=192.168.0.1

3) Modify the/etc/sysconfig/network file as follows:
Networking=yes
Networking_ipv6=no
Ipv6init=no
Hostname=centos_aaa
gatway=192.168.0.1

4) Restart Service network restart

5) Restart the system shutdown-r now

6) View the new Ip:ipconfig

7) But this time to find the problem, you can access the intranet, but not access to the external network.
It seems that configuring DNS in/etc/resolv.conf does not work, open the prompt as follows:
# Generated by NetworkManager
# No nameservers found; Try putting DNS servers into your
# ifcfg files in/etc/sysconfig/network-scripts like so:
#
# dns1=xxx.xxx.xxx.xxx
# dns2=xxx.xxx.xxx.xxx
# domain=lab.foo.com Bar.foo.com
Check the data that the DNS configuration must be added to/etc/sysconfig/network-scripts/ifcfg-eth6, increase dns1=192.168.0.1.
But this time or not, the last data is missing the default routing settings, need to add the following file/etc/sysconfig/network-scripts/route-eth6, the content is: via 192.168.0.1.
Then you can restart the network.

8) The/etc/hosts file is set up as follows: But it should be not related to IP and DNS configuration issues.
27.0.0.1 localhost.localdomain localhost
192.168.0.120 centos_aaa CENTOS_AAA
:: 1 localhost6.localdomain6 Localhost6

9) However, it is found that the static IP does not work after the shutdown restart, because the network service is not set to auto-random startup and is modified as follows:
Need to start Network service:
[[Email protected]_aaa ~]# chkconfig Network on
[Email protected]_aaa ~]# chkconfig--list | Less
Network 0:off 1:off 2:on 3:on 4:on 5:on 6:off

10) After restarting the machine only IPv6, no IPv4, need to manually perform service network start to enter a fixed IP4 state. How to solve this problem??? (originally because network and networkmanager two services conflict)
First stop IPv6, add in the last/etc/sysctl.conf:
Net.ipv6.conf.all.disable_ipv6 = 1
Net.ipv6.conf.default.disable_ipv6 = 1
Then stop the NetworkManager service:
Chkconfig--level123456 NetworkManager off
Personally feel that in order to avoid the two service similar function conflict, NetworkManager should not be a service, only should be to the network service of an upper layer of packaging.

Centos6.2 setting up static IP and DNS