There is quite a complete thread about the meaning of this warning.
(cannot mention DL6ER as a new user...) provided a good summary:
The warning is there intentionally and we should not offer a way to simply suppress it. In the end, it tells you that something different than you may expect is happening here. The intention of this mechanism is to constrain hostnames so that an untrusted host on the LAN cannot advertise its name via DHCP as e.g. "microsoft.com" and capture traffic not meant for it.
I partially agree with the rationale (general case of "better worry than sorry") but this is a pain in th bottom for those who have, say, company laptops in their network that advertise a specific FQDN.
While having the ability to hide/disable the warning should be IMHO something that is made available (people who set up their DHCP and DNS at least understand that they will run into problems someday), I was wondering whether it is possible to whitelist the external domain.
If my machine is called mylaptop.company.com and my home network is athome.org (and this is the domain I send via DHCP to all local devices), is there a way to make company.com being recognized as a local domain?