Check DNS servers

In our database we have a list of domain names that we manage with their primary and secondary servers, something like: …. [login to view URL] ? ? ? ? ? ? ? ? ? ? ? ? ? ? [login to view URL] ? ? ? ? ? ? ? ? [login to view URL] [login to view URL] ? ? ? ? ? ? ? ? ? ? ? ? ? [login to view URL] [login to view URL] …. ? We have the problem that some of our clients have changed their DNS servers without informing us. ? We need to know if the domain names that we manage are using the DNS servers that we have in our database, or if they are using other DNS servers. ? To do this check, we need an application that is able to query DNS servers of a list of domains, and then check if the DNS servers that each domain respond, correspond to the ones that we have in our database. ? We will provide a .txt file with domains and DNS servers from our database; file will have this format (tab sperated): …. [login to view URL] ? ? ? ? ? ? ? ? ? ? ? ? ? ? [login to view URL] ? ? ? ? ? ? ? ? [login to view URL] [login to view URL] ? ? ? ? ? ? ? ? ? ? ? ? ? [login to view URL] [login to view URL] …. ? Application should query each domain, retrieve the DNS servers, make the comparison and send to a .txt file the list of domain names that are having a DNS response different to what we have in our database. Application should also list the DNS servers that were found of those domains. ? Application should be multithreaded so it can check several domain names at a time (we probably need to check 10,000 domains every month so we need a fast application). ? If there was a connection error with one domain, application should be able to show this in the output .txt file.