I have two VPS. I would like to use second one as a secondary dns server. both VPS are Debian 6. how I could do that? is it enough that I install bind9 and copy zone files from first VPS to second VPS?
First of all if you want to setup a secondary DNS server you will need to define who is the master and the slave.
For example on the VPS1 server the master entry should like something like that:
On the VPS2 machine where you will run the slave DNS add this entries:
Once you restart both DNS servers the slave server (VPS2) will automatically transfer the zone file from the master (VPS1).
You also need to change the zone file and add the new DNS server. Add a line like that
Now the only thing left is to inform your domain registrar of the changes. Only after that your new NS will be public and used by clients.