For example, you
can create a conditional forwarder to forward any attempt to resolve hosts in
the Microsoft.com domain to a specific DNS server instead of your normal
forwarder server.
Background Zone Loading
Windows Server 2008 DNS includes a number of performance enhancements, including
background zone loading. This feature allows the DNS server to begin responding to
clients almost immediately after it has been restarted; in the past, the server would have
had to wait to retrieve the DNS data from AD DS. Although it can??™t respond to requests
for host information that hasn??™t yet been loaded from AD DS, it can begin to respond to
requests that are designated to be forwarded (for example, requests for Internet sites) for
any host information stored in files.
When a Windows Server 2008 DNS service starts up, it follows this procedure:
1. Enumerates all zones to be loaded
2. Loads root hints
3. Loads all file-backed zones (any zone information not stored in AD DS)
4. Immediately begins responding to clients??™ requests
5. Spawns new threads to load zone stored in AD DS
In previous Windows Server DNS systems, step 4 (responding to clients) was contingent
upon step 5 (obtaining all the zone information from AD DS) to complete. Naturally,
depending on the number of records your DNS hosts, this could be a very lengthy
process, effectively neutering your DNS server until it has retrieved the requisite data.
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