Exchange 2010 Lose connectivity to GC . Event 2012 , 2013 , 2070 log

Hi All ,

I have very similar cases with below link .Intermittent few week CAS seem like hang , users outlook unable to connect . After reboot the CAS server , everything back to normal . In below article i do not have have 2114 instead of 2070 and only Cas server have event 40961 logged. secondly , all dcs are 2008r2 . So cant apply the hotfix as well

http://www.scottfeltmann.com/blog/2011/11/09/exchange-2010-servers-lose-connectivity-with-global-catalog-servers-in-domain-event-ids-logged-2102-2103-and-2114/

http://social.technet.microsoft.com/Forums/en-US/exchange2010/thread/58c763de-283a-4176-a885-c8d2cb3cfacb

event 2070

Process Microsoft.Exchange.RpcClientAccess.Service.exe (PID=xxx).  Exchange Active Directory Provider lost contact with domain controller xxxx.  Error was 0x51 (ServerDown) (Active directory response: The LDAP server is unavailable.).  Exchange Active Directory Provider will attempt to reconnect with this domain controller when it is reachable. 

anyone face same issue ?