The SBA will be a new registrar and we can treat it as a new Pool. Please make sure you move the branch users from the primary pool to the SBA registrar correctly and the SBA will be their primary registrar. You would usually set the centerl pool as
thrie backup registrar.
Please run Get-CsUserPoolInfo to display a user's primary and backup registrars as well as the order of Front End Servers that the user will register against. You can refer to the following link to check the reason why 301 redirection did not happen.
Microsoft is conducting an online survey to understand your opinion of the Technet Web site. If you choose to participate, the online survey will be presented to you when you leave the Technet Web site.