Misk.com DNS Lookup - Powerful domain name and ip address tools for DNS Lookup (nslookup), Supports Reverse DNS, FCrDNS...
MxToolBox - All of your MX record, DNS, blacklist and SMTP diagnostics in one integrated tool.
intoDNS - IntoDNS checks the health and configuration and provides DNS report and mail servers report.
Audit DNS - Audit your domain name DNS settings easily and quickly.
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