Nutanix Updated NCP-BC-7.5 Exam Questions and Answers by indigo

Nutanix uses a " Roll-up " retention strategy to optimize storage while maintaining a range of recovery options. This strategy keeps all high-frequency recovery points for the most recent period and then consolidates (rolls up) older snapshots into daily or weekly points as they age.

For a policy with a 1-hour RPO and 5-day retention, the system is designed to provide granular recovery for the immediate past. By default, Nutanix retention logic maintains the hourly snapshots for the current 24-hour window. As snapshots move past the 24-hour mark, they are " rolled up " into a single daily snapshot to save space while still providing a 5-day historical view. Therefore, after six days of operation, the administrator will find approximately 24 hourly recovery points for the most recent 24 hours, followed by several daily recovery points representing the previous four days. This approach balances the need for surgical " point-in-time " recovery (to combat recent data corruption or ransomware) with the need for long-term historical data, ensuring that the BCDR solution is both effective and storage-efficient.

The primary purpose of a Test Failover is to validate the recovery process in a non-disruptive manner. When a VM is recovered from a snapshot during a test, it retains its original configuration, including its IP address and hostname. If this test VM were to be powered on on the same network as the live production VM, it would immediately cause a duplicate IP address conflict and potentially disrupt production services or trigger security alerts.

To prevent this disruption, Nutanix Recovery Plans allow administrators to map the production network to a " Test Network " at the recovery site. This test network is typically an " Isolated " VLAN or overlay network that has no physical or logical route back to the production environment. By using an isolated network (Option A), the test VMs can boot up, run their internal services, and even communicate with other test VMs (if placed on the same isolated segment) without any risk of interfering with real users or databases. This allows the infrastructure team to verify that the " Recovered " state is functional while the " Primary " state continues to serve the business, fulfilling the core requirement of non-disruptive testing.

Replication between Nutanix clusters involves the transfer of both actual data blocks and the metadata required to manage the consistency and scheduling of those snapshots. Two specific services running on the Controller VMs (CVMs) are responsible for these tasks: Stargate and Cerebro.

Port TCP 2009 is used by the Stargate service. Stargate is the primary I/O manager for the Nutanix cluster, and in a BCDR context, it handles the " Snapshot-on-wire " data transfer. This is the port where the actual bits of the virtual disks are sent from the source cluster to the destination cluster. Port TCP 2020 is used by the Cerebro service. Cerebro is the replication engine that handles protection domain orchestration, snapshot scheduling, and cross-site handshake operations. Without port 2020, the clusters cannot synchronize their schedules or confirm that a recovery point has been successfully stored at the remote site. While other ports like 9440 (Prism management) and 22 (SSH) are used for administrative tasks, ports 2009 and 2020 are the mandatory " data path " and " control path " ports required for the continuous and successful replication of workloads between availability zones.

Synchronous replication is designed for zero data loss by requiring that every write be acknowledged at both the primary and recovery sites before the application can proceed. This creates a " hard " dependency on the network link between the two clusters . If the network connectivity is interrupted (e.g., during scheduled maintenance), the primary cluster will be unable to receive acknowledgments from the remote site.

By default, if the synchronous link is broken, the primary cluster may pause I/O to the protected VMs to prevent data inconsistency, which would cause the VMs to become unresponsive to users. To prevent this during planned maintenance while ensuring that the VMs stay online at the primary site, the administrator should temporarily transition the protection mode. Changing the Protection Policy from " Synchronous " to " Asynchronous " (Option C) removes the real-time write-mirroring requirement. This allows the VMs to continue serving local I/O independently of the remote site ' s status. While this technically increases the RPO during the maintenance window, it ensures application availability. Once the maintenance is complete and network connectivity is restored, the administrator can change the policy back to Synchronous. The system will then perform a catch-up sync and return to the Zero-RPO state once the data at both sites is identical again. This operational maneuver is a standard best practice for managing " stretched " cluster environments during infrastructure updates.