I'm using http://DNSStuff.com It's comprehensive, but HTML validator is not good. I use one of these two, they are the same: http://VALIDATOR.w3.org http://w3schools.com/site/site_validate.asp http://centralops.net/co/ http://www.iwebtool.com/ (awesome tools, but you can only use one by one) are also good. Question: Any other comprehensive all-in-one DNS tool (IP, IP geolocation, IP class, DNS record, WHOIS, traceroute HTML validator, PR...,exact time of domain's settings update.