A reality of any system is that temporary things become permanent and some of the brightest can do dumb things.  Sometimes cleaning up a messy setup still leaves some hard points that just can't be changed.

Either way we sometimes end up with excluding IPs from a range, enough that just splitting pools is a very ugly work around.

Being able to exclude an IP from a DHCP Pool/IP range would go long ways to simplifying this.  It is something we had way back in NetWare days where we could easily set a single IP to be reserved.  I would make administrative life easier in many environments as the image of perfection is just a fantasy.

Two scenarios are :

- a static IP that the DHCP just ignores.

- a DHCP IP that is always only handed out to one fixed host, such as by selecting an existing assignment and selecting either permanent or a much longer lease than the rest of the pool/range.