Windows sometimes has a mind of its own when it comes to DNS. To clear the windows DNS cache when you have issues do the following. Open cmd or powershell as administrator. Run ipconfig /flushdns

To reset (flush) the DNS cache on Mac OSX depends on the OS version. One of the following commands in the terminal should do it for you. sudo dscacheutil -flushcache or sudo killall -HUP mDNSResponder or sudo discoveryutil mdnsflushcache

The simplest way to reset the DNS cache on your iphone is to switch it to Airplane mode and back. Airplane mode switches of all network connectivity, this has the side effect of clearing the DNS cache.

Updated 23 February 2021 Cloudflare is a Content Delivery Network (CDN) service with a free basic offering. To provide the content delivery service they need to manage your DNS and provide a very nice interface to set up DNS. You can use the free DNS service without making use of the rest of their services. If you use Cloudflare for DNS it is adviseable to use their reverse proxy (CDN) service. It really speeds up your site and also provides some protection against attempts to hack your site. If you use a system like Wordpress for your site you will find many articles on the web to assist in setting up Cloudflare correctly e.g. how to stop /wp-admin from being cached. Read more