FYI = For Your Information
i just configured a caching only server becz at that time i couldn't make a difference between master , slave and caching.
AM i right or not plz. clarify.
Technically, a caching-only server does not load any authoritaive zones, just the root (hint) and localhost reverse zones. In short, a caching-only server caches (stores in RAM) all queries that its asked to resolve by clients configured to use this server. It's not authoritative for anything.
So by definition, the DNS server you configured in the other thread is no longer a caching-only DNS server. Why? Because it now loads a couple of authoritative zones for your private network. But it still caches all non authoritative queries just like a "caching-only" server would, but it also answers authoritaive queries for your private domain. Which is good!
With reagrds to the master/slave designation - The terms master/slave are only meaningful among the configured DNS servers. i.e. I'm not aware of a RR type that returns a master/slave designation. A DNS server configured to load a zone as a slave will transfer its authoritative copy of that zone from the DNS server that loads the same zone name as a master. But heres the kicker (and the source of confusion for people learning DNS)... DNS servers use a round-robin algorithm during a query that involves recursion. So if your domain name lists two name servers as authoritative (one master, one slave) a remote DNS server (like mine) will alternate queries between the two name servers to fetch answers. It will not query the so called master name server first (everytime), and if no answer is received (server down), query the slave. In fact, ISP's like yahoo, use this round-robin algorithm to distribute bandwidth among multiple servers. Checkout how many servers are listed for www.yahoo.com
If you want to visually see round-robin in effect, try using dig +trace for the same domain name multiple times and watch where the responses are received from. Especially from the TLD name servers.
BTW: When you are ready to test your DNS server (should you register your domain) , checkout: www.dnsstuff.com