Why CentOS doesn't run eth0 in startup?

In `ifconfig` there is only the `lo` interface. I must type

```
service network restart

```

to run interface eth0, why?

network-scripts eth0:

```
DEVICE=eth0
HWADDR=00:1D:09:67:E2:FB
TYPE=Ethernet
UUID=b6e7650e-b2e8-419e-ac6b-a26941053d2d
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=dhcp

```