Experimente grep -i dhcp /var/log/messages
. Eu acho que por padrão no CentOS o DHCP irá logar lá. Deve mostrar DHCPREQUEST e DHCPACK.
Apr 12 05:05:29 dart-dev dhclient[928]: DHCPREQUEST on eth0 to xxx.xxx.219.73 port 67 (xid=0x7d478419)
Apr 12 05:05:29 dart-dev dhclient[928]: DHCPACK from xxx.xxx.219.73 (xid=0x7d478419)
Apr 12 05:05:29 dart-dev NetworkManager[852]: [1523534729.3637] dhcp4 (eth0): address xxx.xxx.15.81