DNS

I am studying for my MCSA and I was using testout for the 291. This answer and explanation just does not seem right to me. Tell me your thought.


How can they expect to ever make it to there external dns server for their own external lookups or Internet lookups. When the secondary dns server wont even be contacted unless the primary domain server does not respond. Oh and by the way I also assume they mean perfered "primary" and alternate "secondary" since clients have no knowledge if servers have primary or secondary zones.
From what I have read I understand that the second dns server is not ever contacted unless the first one does not respond its a matter of fault tolerance incase the first server does not respond and is not available.