SecurityTrails helps you prepare so you’re never blindsided or embarrassed by an attack you could have prevented. Source: SecurityTrails | The World’s Largest Repository of Historical DNS data
You can tell your Mac to use a Host File instead of your DNS to go online. Here’s how! Source: How to edit your Mac’s Hosts file and why you would want to
intoDNS checks the health and configuration of DNS and mail servers. Source: intoDNS: checks DNS and mail servers health
Source: DNS check tool