We need to explain Range in Subnet form better, we do this in our manual but I doubt people see this. Let's create a help bubble with this text:

While it is possible to define the same DHCP range in Foreman, it’s usually good practice to select a range from outside the pool defined in the installer, but still in the subnet. For the example above, it is recommended to define the DHCP range from 10.0.0.1 to 10.0.0.99 in the Foreman UI which gives the following IP address distribution:

• 10.0.0.1 - 10.0.0.99 - addresses reserved during bare-metal provisioning by Foreman
• 10.0.0.100 - 10.0.200 - addresses for dynamic clients in the subnet (discovered hosts, unmanaged hosts)

https://theforeman.org/manuals/1.20/index.html#3.2.3InstallationScenarios