How to find out if an XML-RPC server is working?

I have a huge Ping list and want to clean it.

Using PHP I have already removed duplicated, checked 开发者_StackOverflowfor 404s, redirects etc.

I was wondering what I could send to the URLs to see if they are actually functioning and open for submissions?

There is the XML-RPC Introspection de facto standard which you could try first. If the server doesn't offer introspection you could just try to send a randomly generated method call. If it is a working XML-RPC Server you should get back a fault object.