Nameserver usage

I have four nameservers registered for a domain:

ns1.primary-nameserver.net
ns2.primary-nameserver.net
a.ns.secondary-nameserver.net
b.ns.secondary-nameserver.net

How can I find out how much usage each nameserver is getting? Or is it safe to assume that it's 25% to each?

Update

I don't control the nameservers, they are provided by third party suppliers like DNS Made Easy, Zerigo, Route 53, etc. I am trying to establish whether all listed nameservers are used equally.

Solution 1:

If your dns servers are running bind you can enable, if not already done so, the statistics file.

This can be done with putting statistics-file “/var/stats/named.stats”; in the global section of your named.conf. After you have restarted your bind you can run rndc stats and it will show you the statistics of the server.

So to get the usage percentage of your namesservers you have to collect all the rndc stats outputs and calculate it yourself.