Add a 'blockedif' parameter for checking what IP is returned from DNS answers

[Taarek]

What would you like to add or change?:
When you configure DNS servers there is this parameter, and I would like to have a sub-parameter for checking what the returned IP address is from the DNS query.

Why do you and others need this?:
Because Fortigate firewalls (and probably others) tend to reply with an IP address for their "You have been blocked" page. So would be nice to be able to handle this in a good way, esp on a work laptop when you jump in and out on different networks, and sometimes office network.

Here is an example of how it may look like, so using empty, refused or zeroip does not work for my usecase, sadly.

[dhaavi]

Hey @Taarek, thanks for the suggestion.

I think this is a good idea. I will look into it.