Two forwarders in my internals name servers

[Miriam Benham]

I have a primary and secondary dns in the public segment pointed like
forwarders for the internal name servers.

What I notice is that when the primary name server goes down and the
secondary became in place to process the queries, the resolution from the
same internal host take times and it brings me this error.

DNS request timed out.
    timeout was 2 seconds.

When I'm browsing it take time and fail, but if I try the same site again it
brings me the page. Every time I have to try twice the addresses to be able
to reach these.

Can somebody tells me what's going on.