DHCP / Static Addressing Hybrid

I don't think you can do that. Even with DHCP clients on Linux, the best you can do is ignoring the gateway and other options. But for the IP configuration, you can't separate the host address and the netmask (or peer IP on a peer-to-peer link).

I hope you don't want to set up a network with different netmasks because that literally at least breaks all the software that relies on broadcast traffic.

Why can't you just set a different subnet mask on your DHCP server? Even the crappiest router should allow that.

>>60309862
I'm inheriting working on a network for the local city hall.

There's an in place surveillance system (with lost credentials, years ago) that operates on 192.168.2.x, and all the workstations are on 192.168.1.x

If I set a static IP on a workstation in the 192.168.1.x range, and a subnet mask of 255.255.248.0, the workstation can interact with everything on the workstation network and all the cameras on the surveillance network.

The mayor wants to be able to view the cameras, but I don't want to set him to having a static address, because the credentials for their domain controller have also been lost, for years, and I don't know how to avoid an IP conflict happening.

>>60310003
The cleanest solution would be to put a router between both networks (assign an IP from both subnets to a port and enable routing between them), but that would require messing with the gateway.

With any Windows Server from at least 2003, you can reset the domain controller password as long as you have physical access with at least a Win2008R2/Win7 install DVD.
https://4sysops.com/archives/forgot-the-domain-admin-password/

>>60310310
I'll take a look into that.

It's a real mess, right now there is no router (other than a resedential grade DSL modem/router) and the entire network is built out of a series of 8 port Netgear resedential switches plugged into each other with the DSL modem / domain controller / security system plugged in at the "top" switch :-|

Godspeed, OP.
Maybe you should think about setting up that surveillance system new while you're at it, too.

>>60310003
sounds like oyu have other problems which you are merely plugging

op just turn on dhcp, note your assigned address, then turn it off and enter the address and whatever subnet mask you want. most dhcp servers lease out addresses for 1200 hours so you should only have to do this every so often. also write a script to do this for you upon login