Top 3 online DNS testing tools

Here is my list of favorite DNS testing tools:"

1. IntoDNS (www.intodns.com)
   Completely free and really sophisticated information about you domain name. 
2. DNS Check (http://dnscheck.iis.se/)
   Also very good tool but not as sophisticated as IntoDNS
3. How is my DNS? (http://www.howismydns.com/tools.php)
   Not my preferred tool but I always use it to cross-check results with previous two tools.

All mentioned tools are free and without any subscription payments or so.

If I had to pick one paid tools I would definitely go with this one:

1. DNS stuff (http://www.dnsstuff.com/)