If you are making any changes to your DNS records or performing a nameserver move, these tools are valuable to check the accuracy of the change and the propagation of the records across the world. They also check for correct record formation and possible vulnerabilities.
DNS Stuff Toolbox – This is the most comprehensive set of DNS tools available on a single site. One of the most useful tools is the DNS Report. This analyzes the DNS records and flags configuration issues
MX Toolbox – A simpler to use tool, has provision for the user to inquire the DNS record entry by record type, including MX records. The user can choose between a drop down selection or use a simple command line prefix.
ViewDNS – Similar to DNS Stuff, has a variety of tools including an usual firewall test for Iran and China. Report formats are very basic. Record lookup only listed NS and A records.
DNS Checker – Checks propagation of DNS records across the world by record type
ICANN Whois – “Who is” is a function that looks up the registration information for a domain name. The ICANN Whois goes straight to the source of the data. Many web hosts have whois functions on their sites, however, you will get their marketing hype and solicitations for buying domain names.