For external:

ADFS is auto failovered by UltraDNS under sitebacker sso.mopt.vic.gov.au

For internal:

1. Login to MRS-RDP server

2. Open DNS Manager

Failover need to be done manually by modifying a A record in DNS server. 

IP address is depends on which server is available.

RLA-ADFS01: 10.21.120.29

MRS-ADFS02: 10.21.120.32