I worked at a place once with an old Win 2k server sitting in the corner of the server room. It had once been a workgroup/domain controller but was long retired

I worked at a place once with an old Win 2k server sitting in the corner of the server room. It had once been a workgroup/domain controller but was long retired from that job. As far as we could tell, nothing was talking to the box anymore and the box wasn’t hosting anything anymore. But for some reason if we shut it down, the network would have random failures to communicate between various devices. It was never especially high priority solve, so we just all knew that we couldn’t turn off that box. Never did find out what was misconfigured before I left.