Exchange 2013 DNS high availability best practices

Change internal and external URL for all virtual directories to the name of loadbalancer of CNAME DNS record (round robin), e.g.
mail.ocean.com

Then in powershell
Get-ClientAccessServer -id *2013* | fl *uri
Get-ClientAccessServer -id *2013* | set-ClientAccessServer -autodiscoverServiceInternalUri https://autodoscover.ocean.com/autodoscover/autodoscover.xml

This configures SCP (service connection point in AD)

For external autodiscover You should create DNS record that point to loadbalancer CNAME DNS record (round robin)