220-1101 Networking Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  RAID 0: Stripes data across multiple disks for increased performance, no fault tolerance.

  Why this is correct

  RAID 0 is a striping configuration that splits data evenly across two or more disks, enabling parallel I/O operations for enhanced read and write performance. However, it provides no fault tolerance whatsoever: if any single disk in the array fails, all data is lost. This trade-off makes RAID 0 suitable for temporary or non-critical data where speed is prioritized over redundancy.

• ✓

  RAID 1: Mirrors data onto two disks for redundancy.

  Why this is correct

  RAID 1 mirrors data by writing identical copies to two disks, creating a redundant pair. This duplication ensures that the array remains fully functional and data is preserved if one disk fails. While read performance can benefit from simultaneous reads from both disks, write performance is slightly reduced because each write must be committed to both drives, and storage capacity is effectively halved.

• ✓

  RAID 5: Stripes data with distributed parity for fault tolerance and performance.

  Why this is correct

  RAID 5 combines block-level striping with distributed parity, calculating parity information for each data stripe and rotating it across all disks. This configuration provides single-disk fault tolerance: if one drive fails, the missing data can be reconstructed from the remaining data and parity blocks. RAID 5 requires at least three disks and delivers a balanced mix of storage efficiency, performance, and resilience, making it a popular choice for enterprise storage.

• ✗

  RAID 1: Stripes data across multiple disks for increased performance, no fault tolerance.

  Why it's wrong here

  This description incorrectly attributes striping, which writes data blocks across multiple disks for performance, to RAID 1. In contrast, RAID 1 exclusively uses mirroring, which writes an exact copy of the entire dataset to a second disk for redundancy. Striping without parity is the defining characteristic of RAID 0, not RAID 1.

• ✗

  RAID 5: Mirrors data onto two disks for redundancy.

  Why it's wrong here

  RAID 5 does not use mirroring; it relies on striping plus distributed parity to protect data. Mirroring is the core mechanism of RAID 1, where identical data is written to two disks, halving usable capacity. RAID 5, requiring at least three disks, uses parity blocks spread across all drives to withstand a single disk failure, consuming only one disk's worth of capacity for redundancy.

• ✗

  RAID 0: Stripes data with parity for redundancy.

  Why it's wrong here

  RAID 0 stripes data across multiple disks with no parity or redundancy. The statement is incorrect because parity is an error-detection mechanism used in RAID 5, not RAID 0. RAID 0 maximizes performance and storage capacity but offers zero data protection if any drive fails.

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