About Secondary NS

[Kevin Darcy]

Sumit Mehrotra wrote:

> Small question :
>
> Do the secondary/slave NS for a zone reply to queries ONLY when masters are down/unreachable or, do they answer some queries on their own, even when the master is functional?

BIND nameservers, at least, will choose among the authoritative servers based on their recorded RTT (round-trip-time, i.e. speed) for previous queries. Resolvers and nameservers
shouldn't really care whether their queries get answered by a master or a slave; one authoritative source is considered as good as any other. Note that "topology" can be used to
override this nameserver-selection behavior somewhat.

So the short answer is: the slaves *will* inevitably receive queries even while the master is up. If they answer slowly, however, then other servers may not query them very
often. Query speed is more important than master/slave status. If you wanted to get really ugly about it, I suppose you could artificially slow the slaves while the master is
up, and then speed them back up again if the master goes down. But that's a helluva way to implement failover...

                                                                                                                                                    - Kevin