Im my last blog post I mentioned how you are able to use conditional forwarders to forward request to specific namespaces / DNS-Zones to specific servers instead of using the general forwarder. This is also sometimes referres as "Forward Delegations".
In this context I mentioned Stub-Zones and promised to explain later what they are. Im my words Stub-Zones are "Dynamic Conditional Forwarders". What a Stub-Zone does: it queries a server you specify for a list of NS-Records, so you've got a list of all name-servers responsible for a zone. Then it'll query the server for the A-Records of the Nameservers of the zone.
You are also able to use Stub-Zones instead of the regular (non-conditional) delegation, also refered as "Reverse Delegation".
Advantage:
Stub-Zones are dynamic - if you add new Nameservers for a Zone the Stub-Zones will get this information and also use the new servers.
Also the Stub-Zones do receive their informations by just querying DNS-Servers instead of requesting a Zone-Transfer. You can even add Stub-Zones for Zones where Zone-Transfers are not allowed.
Disadvantage:
If Firewalls are involved: with a Stub-Zone you cannot specify which DNS-Server of the nameservers responsible for the zone in question is really used to resolve the name. If you have specific ports opened just between some servers in question then a Delegation is better.
Same thing if you would prefer the use of specific servers. For example if you have a Hub Office and some branch offices, and the forest root servers are in the hub office, a sub-domain is spread out in the remote offices. Usually all Cliens and Servers are querying the sub-domains DNS-Servers, however some central systems in the Hub-Office are using the Root-Servers for DNS-Requests. Do you really want those central systems which ask the Root-Domains-Servers for queries in the Sub-Domain to get delegated to a remote server? This "might" happen when you'd be using Stub-Zones. So you want to keep those at your central office.
So there are pro's and con's when it comes to using Stub-Zones instead of (static) delegations.