I've been doing network administration (quite unqualified, I might add) for my company for about 7-8 months. We have an extremely strained HP Proliant (about 5-6 years old) running Small Business Server 2003 with Exchange with about 53 users.
Over the past few weeks the DHCP server has been crashing on it. It has been complaining that a device on 192.168.100.89 is running a DHCP server and causing the issue. We checked this guy's PC out and he wasn't running anything that could disrupt the DHCP.
We did a Wireshark trace and found the MAC address was pointing to a Mac Mini next door. We disconnected it for a few days but still the same issue.
Then, the guy on .89 said he thought the problem was due to his phone. It has a DHCP setting on it and the MAC address matched it after clearing out the stacks of the DHCP. It was connected to his computer via a USB cable so traffic was going out on .89. He disconnected that but unfortunately the problem has manifested itself again.
Any ideas or input would be greatly appreciated as it's turning in to a complete mystery. Is there any way to trace or find out what is causing the issue? Please note our crappy server's DNS is not reliable so "nslookup" and "tracert" commands are usually out of date.
Thanks for your time,