Stop server didn't incur to failover


Hi Experts,

I have a question regarding a fail-over.
We’re using Couchbase 2.5.
The automatic fail-over has been checked in the cluster settings.
After stopping the server using stop server command without manually failing over the node ( that is we didn’t push the failover button in the Couchbase console) the automatic failover didn’t work and the operation on the cluster from the client has been failed.

Is it make sense and work as design?
Actually, I’ve expected that the failover will work after 30 sec although I didn’t make manually failover since the automatic failover activated.

Thanks in advance,