A cloud service provider provisioned four active/active data centers in various locations within the country at 50 miles between each data center. The data centers must provide redundant network infrastructure and always be available to customers. Which two data center design steps must be used to meet these requirements? (Choose two.)

An active/active data center design ensures continuous service availability and optimal performance. A key step is directing user traffic to the geographically closest data center using technologies like Global Server Load Balancing (GSLB), which minimizes latency (A). To maintain service continuity and data consistency across all active sites, application data must be replicated between them. This ensures that if one site fails, the others have an up-to-date copy of the data and can seamlessly take over the full workload, fulfilling the "always available" requirement (E).

B. Implement active cluster in data centers 1 and 2 and backup in 3 and 4: This describes an active/passive model, contradicting the requirement for four active/active data centers.
C. Use asynchronous replication between data centers 1 and 2: At 50 miles, synchronous replication is feasible and preferable for an "always available" active/active design to achieve a zero Recovery Point Objective (RPO).
D. Deploy database services in data center 1 and application layer to other data centers: This split-tier architecture creates a single point of failure for the database and introduces significant inter-site latency.

1. Cisco Press. (2017). Data Center Interconnect. Cisco Press. Chapter 2, "DCI Technologies," Section "Extending Applications Across Multiple Data Centers," discusses the need for both GSLB for traffic management and storage replication for data consistency in active/active deployments.

2. Cisco. (2016). Business Continuance for the Data Center Solution Overview. Solution Overview, Page 3, "Active-Active Data Center." States, "In an active-active data center model, applications are deployed in at least two data centers... Data is replicated between the data centers... Global load balancing directs user traffic to the appropriate data center."