Update dns_dhcp.rst

[cotosso]

add a note : firewall IP outside dhcp range

[filippocarletti]

I think that a note in the manual is not needed.
Let's use a UI validator.

[cotosso]

I think that a note in the manual is not needed. Let's use a UI validator.

A note costs nothing, explains how to properly configure the service, and can prevent some misconfigurations while waiting for a UI validator (about a month and a half wait).

[filippocarletti]

Is the IP inside the range supported or not? Is it simply discouraged?
What happens if the IP is inside the range? Does the service start or not? Does it behave unpredictably?
If it is not supported it should be forbidden by the User Interface, not by a note in the manual.

[cotosso]

Is the IP inside the range supported or not? Is it simply discouraged? What happens if the IP is inside the range? Does the service start or not? Does it behave unpredictably? If it is not supported it should be forbidden by the User Interface, not by a note in the manual.

Of course it should be forbidden by the User Interface, but why not have both?
This way I can already configure the dhcp well and avoid problems in the future.