For clarity to other reviewers: yeah, the issue is that the records hash is keyed on IP by default. That causes issues when you GET /dhcp/:network/:mac as the same IP might belong to two macs, and you'll only get one of them.

I considered altering the code to key on mac, but then you hit the same problem when you GET /dhcp/:network/:ip. So instead I re-index on the fly for mac-centric queries. It seems to work from my tests, but I'd appreciate confirmation from others.