Please read:
https://en.support.wordpress.com/https/
https://en.support.wordpress.com/security/
https://en.support.wordpress.com/ip-addresses/#ip-address-for-domain-mapping
https://en.support.wordpress.com/security/two-step-authentication/
If you do not find what you are referring to answered in those support docs then type modlook into the sidebar tags on this thread for a Staff follow-up. How do I get a Moderator/Staff reply for my question? https://en.support.wordpress.com/getting-help-in-the-forums/#how-do-i-get-a-moderatorstaff-reply-for-my-question Also subscribe to this thread so you are notified when they respond and be patient while waiting. To subscribe look in the sidebar of this thread, find the subscribe to topics link and click it.