Slave DNS server not taking over.

[techjohnny at gmail.com]

Hello, Group:

I've got an Active Directory providing the primary DNS to clients, and
the backup DNS server is running Bind 9 as a slave.

Today, the primary DNS server failed, but the clients still couldn't
resolve, even though I was able to manually use the nslookup, change
servers, and verify that the slave responded to requests made by the
clients.

The clients are using DHCP and have a primary and secondary dns server,
but the secondary doesn't automatically kick in when the primary fails.

The slave dns server is properly receiving requests from the primary
and the zones are all up-to-date.

Thanks,

--TJ