Event ID 2084 occurs and Exchange server loses connection to the domain controllers in an Exchange Server 2010 environment

Assume that you have some Active Directory sites in a Microsoft Exchange Server 2010 environment. You add some Microsoft Exchange servers, in particular, Client Access Servers that have OWA virtual directories configured. When a LDAP response is over 50 MB, Exchange loses connection to the configured domain controller, and then tries to connect all in-site and out-site domain controllers. Finally, Exchange loses the connection and event ID 2084 is logged. When this issue occurs, users cannot connect to the Exchange server. 

To resolve this issue, install the following update rollup:

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

Event Information

Event ID 2084 that resembles the following is logged when Exchange loses the connection:

Event ID: 2084
Source: MSExchange ADAccess
Information DateTime MSExchange ADAccess 2084 Topology "Process MSEXCHANGEADTOPOLOGYSERVICE.EXE (PID=1112). No Domain Controller server is up in the local site 'local site'. Exchange Active Directory Provider will use the following out of site Domain Controller servers: 
Server list

When the domain controller disconnects the Exchange, event 1216 is logged in the Directory Service log:

Log Name: Directory Service
Source: Microsoft-Windows-ActiveDirectory_DomainService
Date: Date
Event ID: 1216
Task Category: LDAP Interface
Level: Warning
Keywords: Classic
User: N/A
Computer: Computer
Description:
Internal event: An LDAP client connection was closed because of an error.

Client IP:
Client IP 

Additional Data
Error value:
8616 The LDAP servers network send queue has filled up because the client is not processing the results of it's requests fast enough. No more requests will be processed until the client catches up. If the client does not catch up then it will be disconnected.
Internal ID:
ID

For more information about Active Directory maximum limits, go to the following Microsoft website:For more information about event ID 2084, go to the following website: