FlashStart - The FlashStart Cloud is a web filter for malware protections and to manage unwanted and offensive internet content.
ViewDNS.info - Free DNS related tools including Reverse IP Lookup, DNS Propagation Checker, Chinese Firewall Test...
OpenDNS Umbrella - Cloud Security
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.
SPS Threat Avert - Is your network protected from DNS Tunneling and DDoS attacks, including PRSD and amplification?
NsLookup.io - A simple and powerful tool for querying DNS records