NameserverChecker.com - Nameserver Checker Tool
OpenDNS - OpenDNS provides faster and safer Internet access for your home or Business.
CheckNameserver.com - Nameserver Checker Tools
NameserverFinder.com - Nameserver Lookup Tool
CleanBrowsing - CleanBrowsing is a family and kid-safe way to browse the web without surprises.
DNS Checker Tool - Check Domain Name System (DNS) records for any website.