when name server receive a query that it does know , server will forward its query to root server .

how can we know if this forwarding query request is successful and what answer it get . is there a log file like query log.

You can do a trace with dig which will show you all servers traversed to reach the answer.

dig +trace @<your server's FQDN> www.google.com

no body care this question?

Hi gbcbooks,

Your question is very difficult to understand, or even if it is a question. Sorry, a possible guess is that English is not your primary language. However please try to restate your question more clearly so that others can offer any responses to it. Perhaps you should cite what exact software you are using, which distribution you are using, and the version of it. There are many logs possible for various server software's however until people know more exactly which you are using, it is difficult for people to offer information about log file names, locations, and the ability to control whether or not you get more logs.

First the only time the root servers are queried is when the DNS server doesn't know the answer to the query. Second that query to the root server is not for the answer but to ask who has the answer. The root server will tell your server where to ask for the correct information. In turn your server will then ask the server with the correct information for the answer.

If you have configured it in your named.conf file then yes there is a log file.