Hi Mayur,
A Highly Available Deployment has multiple components, so I will attempt to break this explanation down. The following link will be referenced for IWA or LDAP authentication with client access internal:
Note: If Active Directory needs to be access externally, leverage SAML logins with ADFS.
A Highly Available Portal requires a load balancer to Load Balanced PortalWebContextURL and the PortalAdminURL endpoints to be set. The ArcGIS Web Adaptors are required when leveraging IWA or LDAP Web Tier Authentication with Portal. If using SAML (ADFS) or built-in Users, the Web Adaptors for Portal are not required.
The Web Adaptors for a Highly Available ArcGIS Servers are also not a requirement. The Highly Available ArcGIS Servers are not authenticating access to content - Portal is - and the Load Balancer will handle directing requests for the ServerServiceURL and ServerAdminURL appropriately. When Federating an Highly Available Server environment, the Load Balanced ServerServiceURL and Load Balanced ServerAdminURL will be used.
Note: THe Highly Available ArcGIS Servers can be deployed as a Multiple Machine Site or as Separate Active/Passive Sites. This is dependent on your needs. The link you referenced explains the advantages and disadvantages of each configuration, however this decision is independent from how the Highly Available Portals and Data Stores are configured.
When registering the ArcGIS Data Store with a Highly Available ArcGIS Server deployment, use the Load Balanced ServerAdminURL. This will also allow Portal to set the Load Balanced Server as a single Hosted Server.
The Standby Data Store will specify the Load Balanced ServerAdminURL. However, this Data Store should display as a Standby machine / Highly Available Role.
In Review:
1. - There are four Load Balanced URLs
-- PortalWebContextURL
-- PortalAdminURL
-- ServerServiceURL
-- ServerAdminURL
2. - Web Adaptors for Highly Available Portal is only required to leverage Web Tier Authentication
3. - Web Adaptors for Highly Available Server is not required.
4. - Data Store is configured for fail over
Let me know if I misunderstood your request or should clarify points in the above information.
- Austin