[CentOS] question on DHCP

If a machine with centos 6.2 is set for DHCP and it looses power and the switch looses power for a long time. lets say a day. so the switch really goes off even with batter backup.

Now power comes on, the machine asks for a DHCP address before the switch is read as its not back up yet. there is no response and the machine does not get an address. Finally the switch comes back up , the machine has already posted that it Network got an error as there was no DHCP server.

Does the machine ever ask again???? or do I have to manually do a server network restart or reboot the machine again.

It seems to never ask again.

jerry