Update OAB Mulitple Times - Exchange 2013 DAG

I am trying to figure out which server is hosting the arbitration mailbox.  The following commands returns no results.

Get-Mailbox -Arbitration | where {$_.PersistedCapabilities -like "*oab*"} 

Get-Mailbox -Arbitration | Where {$_.PersistedCapabilities -match "oab"} | FT Name, Database

I want to config the OAB to Update every 3 hours.  I am reading here.

http://m.msexchange.org/kbase/ExchangeServerTips/ExchangeServer2013/OutlookOWA/generate-exchange-2013-oab-multiple-times-day.html

Thank you