isc dhcp multiple option 240 in same subnet

I'm fairly new to isc dhcp.

I'm working at an ISP and need to provide our STB's with an option 240, and it has worked fine for years, the problem now is that we are getting a newer model, that needs a different option 240 string. How do I do that in the same subnet? Is it possible to match on the mac-address and only provide the correct option 240 string to the corresponding mac.

Best regards Danny

One way is to use classes, there is many examples using that approach and then having different options for the classes.

One other approach is to do something like this.

pool {
  option 240 ... default
  if (substring(hardware,1,3) = 11:22:33) {
    option 240 ... override
  }
}

Or even:

host the_device_name {
    hardware ethernet 11:22:33:44:55:66;
    option 240 ....;
}