Exchange OAB（Offline Address Book）

If Outlook is left running constantly in Cached Exchange Mode, it updates the Offline Address Book automatically about once a day

Outlook clients update the OAB file every 24 hours (it is the running time after last OAB downloading).

So, if you want to see the AD attribute change immediately in Outlook client, you may consider the followoing methods:

Method1. Run Outlook in Online mode;

Method2. Force the OAB update

Q5: How frequently is the offline address book updated on the Outlook client?

A5: If left constantly running, Outlook in cached mode automatically updates the offline address book on the client every 24 hours.

The 24-hour time period is measured from the time that the offline address book was last downloaded successfully.

For example, if you complete an offline address book download at 09:00 today, Outlook will start the offline address book download the next day at approximately 09:00.

Therefore, different people will receive updates at different, random times.

https://support.microsoft.com/en-us/kb/841273

1、Exchange Offline Address Book離線通訊錄

2、OAB設置：每天4:00、7:00、8:00、13:00、16:00、19:00 OAB 更新數據

3、CAS設置：每60min，CAS同步OAB

4、OUTLOOK設置:個人可以設定

脱机通讯录OAB

是Exchange基础架构中的关键组件，OAB由Microsoft outlook客户端在脱机时在缓存Exchange模式下用于通讯薄查找。OAB还减轻Exchange服务器上的工作负载起着重要作用。因为缓存模式Outlook客户端将始终先查询本地OAB。

Exchange2007中的OAB:

引入的OAB的web分发，以及cas服务器角色（主要负责分发OAB）。但OAB生成过程本身并未发生太大变化。

Exchange 2013中OAB的修改

那个服务器生成OAB？

以前版本的Exchange中，OAB生成由Server属性绑定到特定的Exchange服务器，安装第一台Exchange邮箱服务器时，安装程序会将其执行为OAB生成服务器。

在Exchange2013中，OAB由托管特殊类型的仲裁邮箱的每个Exchange2013邮箱服务器生成。OAB生成，不再由server参数绑定。

Get-offlineaddressbook "default offline address book' | fl name,server

Exchange 2010中的OAB：

get-offlineaddressbook "default offline address book" | fl name,server

此方法的缺点在于只为OAB生成配置了一台服务器，它是单点故障，如果服务器长期不可用，则会影响OAB生成。

那个组件将生成OAB？

Exchange系统助理服务是负责以前Exchange版本中的OAB生成的骨干。OAB生成是计划的过程，OAB生成将于在OAB属性上配置的计划时间启动，无论服务器上工作负载如何。

OAB文件存储位置

%ExchangeInstallPath%\ExchangeOAB文件夹中

Exchange2013中，生成的OAB文件先存储在组织邮箱中，稍后会复制到%ExchangeInstallPath%\ClientAccess\OAB文件夹