SUMMARY
Exchange 2000 clustering does not support Network News Transfer Protocol (NNTP) components. However, you can use a master/subordinate arrangement (previously known as master/slave) to increase NNTP reliability.
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Configure Master/Subordinate Arrangement
With a master/subordinate arrangement, newsgroup information is kept on more than one server. Keeping newsgroup information on more than one server reduces the impact in situations where a server becomes unavailable. One possible configuration is to use one master server and one or more subordinate servers. With such a configuration, you can configure your newsgroup DNS in two ways:
- Configure DNS so that users access newsgroups through a specific subordinate server.
- Configure DNS using round-robin DNS so that users access newsgroups through any available subordinate server. Round-robin DNS offers additional reliability because users can continue to use all newsgroup functionality even if one of the subordinate servers becomes unavailable.
Note: When you set up your NNTP master/subordinate arrangement, configure a feed from each subordinate server to the master server. Do not configure any feeds between subordinate servers.
To configure the master/subordinate arrangement:
- Select one server to be the master server, such as master news server (mynewsserver.ms.com).
- Point to three subordinate news servers (subordinate1.contoso.com, subordinate2.ms.com, and subordinate3.ms.com) that will be the subordinate servers.
- You can also configure a round-robin DNS so that users will gain access to newsgroups through either subordinate1, subordinate2, or subordinate 3.
With this configuration, when a user connects to the newsgroups from his or her browser, he or she is routed to one of the subordinate servers (for example, subordinate1). When the user posts a message to subordinate1, the message replicates to the master server, and then the master server replicates the message to subordinate2 and subordinate3. That new message post is not available to any users (that is, the message cannot be seen by any users) until it successfully replicates to the master server. After the replication occurs, each subordinate server contains the same content.
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Troubleshooting
Master Server or Subordinate Server Failure
If the master server becomes unavailable, users can still view the messages in the newsgroups. They can even create and submit new posts. However, any new posts created on any subordinate server while the master server is unavailable will not be available to any users. The new posts are not available because the master server has not replicated them to the subordinate servers. Each subordinate server holds any pending posts until the master server is available. After the master is available, it accepts any pending posts, and then replicates those messages to the subordinate servers. After replication occurs, each subordinate server contains the same up-to-date content. In this scenario, the only temporary interruption of service to users is that newly posted messages cannot be viewed.
If one of your subordinate servers becomes unavailable, and if you configured your NNTP to use round-robin DNS, your users have full newsgroup functionality because they can connect to another available subordinate server. In this scenario, remove the IP address of the unavailable subordinate server from your round-robin DNS configuration. After you remove the IP address of the unavailable subordinate server from DNS, users who connect to the newsgroups will be pointed to one of the available subordinate servers. If you do not remove the IP address of the unavailable subordinate server, users will continue to be routed to the unavailable subordinate server. If any of your users were connected to the subordinate server when it became unavailable, they must restart their browsers to continue using the newsgroups because they may have cached information specifying the now unavailable subordinate server. When the subordinate server becomes available again, you must reconfigure the NNTP round robin DNS to include the IP address of the subordinate server.
If one of your subordinate servers becomes unavailable and your NNTP does not use round robin DNS, your users who gain access to newsgroups through that unavailable subordinate server will lose all NNTP functionality. In this scenario, you must change your configuration so that users who access newsgroup information on the unavailable subordinate server can access newsgroups through one of your other subordinate servers. After the subordinate server is available again, reconfigure your NNTP access to the subordinate server so that users can access newsgroups through their original subordinate server.
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Master Server and Subordinate Server Newsgroup Hierarchy Considerations
When you use a master/subordinate arrangement, keep in mind the following considerations:
- When you create newsgroup hierarchies, only newsgroups that are created using control messages will be automatically created on the subordinate servers. For more information about using control messages, see the Exchange 2000 online documentation.
- Newsgroups that are created by using System Manager or by using the Rgroup.vbs command at a command prompt do not replicate to other subordinate servers until a message is posted to the group on the master server. For more information about using Rgroup.vbs, see the Exchange 2000 online documentation.
- Users cannot post messages on a subordinate server until the newsgroup to which they want to post has been replicated to that subordinate server.
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Replicate Hierarchy to Subordinate Servers
After you establish your newsgroup hierarchy, replicate it to the subordinate servers by doing one of the following:
- Post a test message in the group on the master server.
-or- - Create exactly the same hierarchy on each subordinate server.
-or- - Create your newsgroups using control messages.
For more information about NNTP master/subordinate arrangements, see the Exchange 2000 online documentation.
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