一旦找到，就表示主服务器不可用，需要立即开始监测连接性。

Once you find this, you know that the primary server is unavailable and that you should begin to monitor for connectivity.

youdao

这些就绪后，当主服务器不可用时，就会通知网络框架。

With this in place, the network framework is notified when the primary server is unavailable.

youdao

如果RADIUS服务器不可用，则使用NAS的本地用户数据库密码。

If a RADIUS server is not available, use the NAS's local user database password.

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