dhcpd stopped responding.

Hi,

My dhcpd on RHAS4 has stopped responding to requests. There are plenty
of interfaces and VLANs throughout our campus and the dhcpd was
providing IP's from different classes for each building etc. and
everything was fine until this morning.

Some of the computers are now unable to obtain IP's. when manually
assigned it works and then the PC even pings the dhcp server.

During a request, there is no log recorded within /var/log/messages.

How do I trace the problem ? Is there any log recordings for the dhcp
apart from the dhcpd.leases ?

Regards.