Unable to connect to network in CentOS 6.3

When I was installing openldap-server and openldap-client in CentOS 6 inside VirtualBox, I was encountering following error.

Could not retrieve mirrorlist http://mirrorlist.centos.org?release=6arch=i1386&repo=os error was
14: PYCURL ERROR 6 - "Couldn't resolve host 'mirrorlist.centos.org'"
Error: Cannot find a valid baseurl for repo: base

Googling around only realize that the default installation doesn't configure to network interface, whereas it is configure to Network Manager. To fixed this, make sure following thing has been done.

1. Attache to Bridge Adapter in VirtualBox network setting.
2. Set NM_CONTROLLED="no" and ONBOOT="yes" in /etc/sysconfig/network-scripts/ifcfg-eth0.
3. Last but not least, send a reboot command.

Cannot enable network after CentOS 6.3 fresh install The NM_Controlled option would be Network Manager controlled and that would mean that you would control interfaces through network manager vs the ifup, ifdown methods.
The option to include Bridged vs Nat in the virtalbox option will assign a separate ip address to your vm in the same ip network as your physical machine, while the nat option would translate the ip of your vm in your virtual network (inside the virtualbox) into the ip address of your physical machines. It's the same approach as NAT in a home lan connecting to the internet through one router.