Tools
A list of DNS Tools to help you analyse your website.
IntoDNS
Analyses various aspects of advanced DNS and provides warnings for areas that should be fixed.
IP Tools
Huge array of DNS tools including DNS lookup, spam database lookup, ping, ISP cache status, IP routing lookup and more.
UltraTools
Quality DNS tools, including a Domain Health Report that tests a domains DNS for a range of common DNS issues. Requires free signup for access to full reports, but worth it IMO.
DNS Tools
Simultaneously check DNS resolve IP, domain Whois, IP whois, check any port and ping the host.
DNS Stuff
Basic free and paid service. Free tools include IP traceroute, Whois and IP location.