Why is deploying four NetScaler appliances - two in the primary and two in the secondary datacenter with a NetScaler virtual server binded to a redirection policy, the best remote access design?

A redirection policy on a NetScaler virtual server, especially in a multi-datacenter deployment with four appliances, is designed to intelligently steer end users to the optimal primary datacenter. This ensures a secure and reliable connection by directing them to healthy and appropriate resources, and it can be cost-effective by preventing unnecessary traffic over expensive WAN links.

While redundancy is a component of four appliances in two data centers, the specific mention of a 'redirection policy' points to optimizing user access paths rather than general WAN traffic optimization.

Redirection policies are used for traffic management and steering, not for segmenting the Gateway and load-balancing features within the appliances.

While NetScaler provides SSL VPN and supports remote access, the primary benefit of a redirection policy in this context is intelligent traffic steering for primary access, not just general expansion or SSL VPN functionality.