Free D-ISM-FN-23 sample questions

Correct answer: Synchronous replication

Synchronous replication is the only method that can achieve a near-zero Recovery Point Objective (RPO). It works by committing a write I/O to both the primary and remote replica sites before sending the acknowledgment back to the host. This ensures that the replica is always identical to the source, resulting in no data loss upon a failure. Asynchronous replication introduces a delay, leading to potential data loss (a non-zero RPO). Snapshot replication is periodic and cannot meet a near-zero RPO. Log shipping is typically used for databases and also has a non-zero RPO.

Correct answers: Variable-length block deduplication; Global deduplication

Variable-length block deduplication is highly effective in virtualized environments because it can identify common data sequences even when they are not perfectly aligned on fixed block boundaries, which often happens with VM disk files (VMDKs).

Global deduplication is crucial because it compares data blocks across all VMs and all backup jobs in the entire system, not just within a single VM or job. Since many VMs share common OS and application files, global deduplication can find and eliminate these redundancies on a massive scale.

Correct answer: 2

To restore from a differential backup, you need the last full backup and the most recent differential backup. In this scenario, that would be the full backup from Sunday and the differential backup from Thursday night. Therefore, only two backup sets are required for the complete restore.

Correct answer: Deploy an archiving solution that moves inactive data to a lower-cost object storage platform with WORM (Write-Once, Read-Many) capabilities enabled.

This solution directly addresses all requirements. An archiving solution is designed for long-term retention and will move data off the expensive primary storage, reducing costs. Object storage is a cost-effective tier for archived data. Enabling WORM (or object lock) provides immutability, protecting against ransomware and fulfilling compliance needs. Backup is for recovery, not long-term retention. Replication is for availability, not cost reduction or archiving. Adding more primary storage is the opposite of the desired goal.

Correct answer: The write is acknowledged to the host only after it has been successfully committed to storage at both the primary and remote sites.

This describes synchronous replication. To guarantee zero data loss (RPO=0), the write operation must be completed and confirmed at the remote site before the host application receives the acknowledgment. This process ensures the sites are perfectly in sync but adds latency to the write operation equal to the round-trip time between the sites.

Correct answer: Array-based migration with built-in storage virtualization

Modern arrays like Dell PowerStore often have built-in migration tools that use storage virtualization. These tools can import LUNs from legacy arrays and perform the data copy in the background while the application remains online. The final cutover involves a brief I/O pause to remap paths, which easily meets the sub-10-minute downtime window. Backup/restore is an offline process with significant downtime. Host-based migration adds overhead to the host and can be complex.

Correct answer: False

This statement describes the purpose of a backup, not an archive. A backup is used for operational recovery (restoring data after loss or corruption). An archive is used for long-term retention of data that is no longer actively used, typically for compliance, legal, or historical purposes. Retrieval from an archive is generally slower than from a backup.

Correct answer: Only the newly inserted clip and a small amount of surrounding data will be transmitted.

This is the primary advantage of variable-length block deduplication. Unlike fixed-length, which would see all subsequent blocks as new due to the shift, variable-length deduplication uses a sliding window to find block boundaries based on the data content itself. It will identify that only the beginning of the file has changed and will quickly re-synchronize, recognizing the rest of the file's data as duplicate blocks that already exist on the target. Therefore, only the new data needs to be sent.

Correct answer: It provides disk-based speed for backup and restore operations while retaining tape for long-term storage.

A VTL uses disk storage that emulates a tape library. This allows the backup software to write data at high, disk-based speeds, significantly shortening the backup window. The VTL can then de-stage the data to the physical tape library in the background for long-term, low-cost retention. This combines the performance of disk with the economics of tape.

Correct answer: To provide continuous service availability in the event of a server failure.

The primary purpose of a failover cluster is to provide high availability. If one server (node) in the cluster fails, the services and applications it was running are automatically and quickly restarted on another healthy node in the cluster. This minimizes downtime and ensures the service remains available to users.