Dnsstuff - DNSstuff offers DNS tools, Network tools, Email tools, DNS reporting and IP information gathering.

DNSChecker.org - Check DNS Propagation worldwide. DNS Checker provides name server propagation check instantly. Changed nameservers so do a DNS lookup and check if DNS and nameservers have propagated.

MxToolBox - All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.

Whats My DNS - Instantly check your domain names current IP address and DNS record information against multiple name servers located in different parts of the world.

SolveDNS - SolveDNS works to check your name servers, a records, and mail servers, SOA records for errors, consistency, efficiency and speed using several DNS tests.

NsLookup.io - A simple and powerful tool for querying DNS records