DNS troubleshooting
- http://www.dnsinspect.com/ **** great info to get
- http://www.intodns.com/ check your DNS settings
- http://viewdns.info/
- http://www.dnsqueries.com/en/
- https://check-host.net/ check your host from various countries
- https://www.ipvoid.com/ IP Address Tools Online
SPF check
Free Public DNS servers
Setup Secure DNS