Do I need to add a slave zone for each domain name I add, in addition to the master zone? Or is the slave zone created automatically?

I couldn't find the answer posted anywhere here or in the tutorials.

You don't need it, everything is managed by nsX.linode.com you have setup in your domain registrant.

If you're strictly using the Linode DNS manager and nameservers, then no. Your master zone is replicated to all nameservers, any of which can respond authoritatively. So technically there is no slave zone.

Now, if you're operating your own nameserver with the master zone (say on your own Linode), then yes, you do need to add a slave zone definition in the Linode DNS manager if you wish the Linode nameservers to also answer on behalf of your zone. In that case each of the nameservers will act as slaves to your master server (and will also respond to notifies you master server may send).

-- David

Thanks so much guys. This linode community has been very helpful!