辅助DNS服务器直接从主d NS服务器传输其区域信息，并在本地保留副本。

Secondary DNS servers transfer their zone information directly from the primary DNS server and keep a copy locally.

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结果是服务器、本地副本各自保留自己的编辑，而二者都没有意识到它们已经不同步。

The result is that the server retains its own edits, and the local copy retains its own edits, and neither realizes that they are out of synch.

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因此，客户端就能够保留一份本地推衍的服务器历史记录副本。

Thus, they will be able to maintain a locally-inferred copy of the server's history.

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