Could you please help me to discover what might be causing a 15 minute broadcast on port 68. This occurs 24 hours a day and is not caused by client PC's or other servers on the LAN. I can only suppose that the DNS or DHCP is refreshing but I can not be sure exactly. This event has been going on for months and our ISDN phone charges are astronomic! The only way that I seem to able to stop this broadcast on subnet 255.255.255.255 is to create an ISA rule blocking all UDP port 67 and 68 traffic. However, this is not the ideal solution since DNS updates do not appear to work and I would really like to know why. Thanks Alan