Is it a good GIS system design to architect a second ArcGIS Server as a failover? If so what would the DNS Alias structure look like?

[RickSanders1]

I have a client who wants to build their system as follows:

In their system design they want to architect a second ArcGIS Server as a failover?  If so what would the DNS Alias structure look like?  Notice the other "Standby" or failover components.  110 users currently, but hope to expand.

I proposed no need for failover:

[RickSanders1]

Yes Marco, I have visited the link to the System Design Strategies wiki - there is a lot there I still need to digest.  Thanks