arthru

Description of the issue/feature this PR addresses: see #3165

dns check should be made against a domain authoritative server

1

Dns checks are made using the local dns resolver or a configured one. By using a non authoritative resolver, we have to wait for dns propagation to be made, that...

The use of a function name as a string is deprecated but still used in the doc... this pull request fixes it :)

Some users might be disturbed when using @cached on a view function. This just adds a warning to help them.