Hello

The internal client if have AD access use scp record http://goo.gl/bKe9yl , but if you have got 3 server why not use wnlb /if DAG not configured/ or dns round rubin an

Hi Willwally,
I hope you have configured your outlook with single name space. if not please check this.
As commented by Sneff you can use WLNB (windows network load balancing) and point autodiscover to the VIP of NLB cluster.
If your using DNS RoundRobin create 3 autodiscover A records and delete failed server A record when a server fails.

FYI WNLB is not at all recommended by Microsoft Exchange Team.
Please check this regarding DNS RoundRobin in Exchange2013. It is supported but not an automatic failover system.
 

Hi Willwally,
I hope you have configured your outlook with single name space. if not please check this.
As commented by Sneff you can use WLNB (windows network load balancing) and point autodiscover to the VIP of NLB cluster.
If your using DNS RoundRobin create 3 autodiscover A records and delete failed server A record when a server fails.

FYI WNLB is not at all recommended by Microsoft Exchange Team.
Please check this regarding DNS RoundRobin in Exchange2013. It is supported but not an automatic failover system.