DNSdumpster.com - Open source domain intelligence lookups for security recon
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.
ViewDNS.info - Free DNS related tools including Reverse IP Lookup, DNS Propagation Checker, Chinese Firewall Test...
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.
Flagfox - Flagfox is a Firefox extension that displays a flag depicting the location of the current websites...
NsLookup.io - A simple and powerful tool for querying DNS records