Cool stuff:
About DNSCheck
Use this DNScheck to perform a technical check on a registered or as yet unregistered (undelegated) domain.
The result page gives details of any problems detected.
For yet undelegated domainnames, you need to enter the the host names and the IP-addresses of the name servers. Choose the ‘undelegated domain test’ tab for this.
About SIDN
SIDN is responsible for the functional stability and development of the .nl ccTLD domain. As well as registering and allocating .nl domain names, the organisation enables Internet users all over the world to make use of these labels at any given moment by means of the Domain Name System (DNS).
–jeroen
via: DNSCheck.