We have 8 no of CAS servers(cas1,cas2,cas3,....) hosted in Network Load Balancing. some of the Users are complaining that not able to access/login to outlook/OWA etc. There is no issue with Mailbox servers/Databases. We are suspecting that one of the CAS  server hosted in NLB having issue.  How to find which CAS causing issue. Any Exchange shell command to check.

What kind of error users are experiencing?

thanks for your reply, 

Outlook went to disconnected state & for some of users asking password repeatedly.

Hi,

You can try to check the IIS log on each CAS to see if there is any relevant error message.

Please also check your certificate since the user was asked to type password repeatedly.

Thanks for your immediate response.

Yes, i have checked the same, but how many cas servers logs we have to check?? because we have 8 cas servers . What i'm asking is any shell command is there to check the ALL the cas servers health.

Hi Laxman,

Hope this work for you....

One thread for information

http://social.technet.microsoft.com/Forums/en-US/e09750e6-7780-44a8-99d0-07c8d7cd1228/some-not-all-clients-getting-prompted-for-credentials-by-outlook-seems-related-to-cached-mode

Please add an authentication method to the CAS serveradd NTLM.