I was wondering if Vodafone has measures in place to protect itself from DNS amplification attacks similar to what seemed to affect Spark customers recently?

I have noticed that a server in the USA can happily use Vodafone's DNS servers, which seems very strange, because I would have thought that Vodafone should only be allowing DNS access to their customers. Not to the public.

Also does Vodafone block port 53 access on inbound connections to their customers, to prevent attackers relaying requests through hacked or poorly setup routers?