DNSCheck is a program that was designed to help people check, measure and hopefully also understand the workings of the Domain Name System, DNS. When a domain (aka zone) is submitted to DNSCheck it will investigate the domain's general health by traversing the DNS from root (.) to the TLD (Top Level Domain, like .SE) to eventually the nameserver(s) that holds the information about the specified domain (like iis.se). Some other sanity checks, for example measuring host connectivity, validity of IP-addresses and control of DNSSEC signatures will also be performed.