By default, as is was hosted at Datacenter Luxembourg, dotnul services are using the DNS resolvers provided by EuroDNS (they're fast and reliable).
These are : dns1.eurodns.com (80.92.65.30) and dns2.eurodns.com (80.92.67.144).
They'll be used in the following exemples.
http://dotnul.com/DIG/-/dotnul.com,A,80.92.65.30
http://dotnul.com/DIG/-/dotnul.com,MX,80.92.65.30
http://dotnul.com/DIG/-/dotnul.com,TXT,80.92.65.30
http://dotnul.com/DIG/-/80.92.90.253,PTR,80.92.65.30
http://dotnul.com/DIG/-/benj.tel,NAPTR,80.92.65.30
http://dotnul.com/DIG/-/dotnul.com,SOA,80.92.65.30
http://dotnul.com/DIG/-/dotnul.com,NS,80.92.65.30
http://dotnul.com/DIG/-/eu.irc6.net,AAAA,80.92.65.30
http://dotnul.com/DIG/-/mail.dotnull.org,CNAME,80.92.65.30