I end up having to run basically this very setup (on OpenBSD, too) because I have a customer who has a Novell NetWare 5 setup and runs IPX only. Bad times.
I used to run a cluster of DNS/DHCP servers that were the first on site to run 5. The rest were 4.11 until we binned them for 6. Three cream coloured Compaq 3U lumps.
Right, but they weren't running IP and refused to do it. I did set up a /30 so the poor old thing could synchronize its clock via NTP, but that was the only IP it talked.
This one's running (present tense) on a 1 GHz Socket 370 Pentium 3. It's got some weirdness about Pentium 4 and newer CPUs. I think it can be patched up but the client doesn't want to pay for the work because "it's fine like it is." Not worth the headache to virtualize as the first attempt didn't work.
I used to run a cluster of DNS/DHCP servers that were the first on site to run 5. The rest were 4.11 until we binned them for 6. Three cream coloured Compaq 3U lumps.