How to check the RUs (recipient Update Service) Recipient Update Service

This is also an old question. Some friends asked this question: Why can't I find a new user in the global book? The reason is that you may not properly configure the RUs (recipient Update service recipient Update Service), or the service may have problems. The solutions are as follows:
A. verify whether the "showinaddressbook" attribute exists.
B. Verify that the usnchanged value is greater than the msexchserver1highestusn Value
C. Manually run the "recipient Update Service"
D. Set "Default schedule Settings" of "recipient Update Service" to "always run"

The following KB is described in detail.
A. For Exchange Server 2003:
How to: Verify that the recipient Update Service works properly on the http://support.microsoft.com/default.aspx? SCID = KB; ZH-CN; 821908

B. For Exchange Server 2000

How to check the progress of the recipient update servicehttp: // support.microsoft.com/kb/246127