COMPTIA A+ CORE 1

RAID 0

RAID 0 (Data Striping) requires a minimum of 2 physical drives and provides 0 fault tolerance (zero redundancy, meaning a single drive failure destroys the entire array), but it maximizes performance by writing sequential data blocks simultaneously across all disks to achieve 100% storage capacity efficiency.

RAID 1

RAID 1 (Data Mirroring) requires a minimum of 2 physical drives and provides 1 drive fault tolerance by duplicating identical data onto both disks in real time, delivering high data availability at the cost of a 50% storage capacity reduction.

RAID 5

RAID 5 (Striping with Distributed Parity) requires a minimum of 3 physical drives and provides 1 drive fault tolerance by distributing data blocks along with parity information across all drives, balancing fast read speeds and hardware redundancy with a total usable capacity equal to N - 1 drives.

RAID 6

RAID 6 (Striping with Dual Distributed Parity) requires a minimum of 4 physical drives and provides 2 drive fault tolerance by calculating and distributing two separate parity blocks across all drives, allowing the array to survive up to two simultaneous disk failures with a total usable capacity equal to N - 2 drives.

RAID 10

RAID 10 (Striping over Mirrored Sets) requires a minimum of 4 physical drives (and always an even number) and provides fault tolerance for at least 1 drive failure (and up to 1 failed drive per mirrored pair simultaneously) by combining RAID 1 mirroring sets inside a RAID 0 striped array, offering maximum read/write performance alongside high availability at 50% storage capacity efficiency.

FTP (port)

FTP (File Transfer Protocol) uses TCP port 20 and TCP port 21 together to transfer files between a client and a server, relying on dual channels to keep management commands separate from actual file delivery. Port 21 is the Control Channel, responsible for establishing the initial connection, authenticating credentials, and passing commands and status codes back and forth. Port 20 is the Data Channel, which handles the actual transmission of data streams—such as file uploads, downloads, and directory listings—between the two systems (primarily when operating in Active FTP mode).

SSH (port)

SSH (Secure Shell) uses TCP port 22 to establish an encrypted, secure command-line connection to a remote device, allowing for secure remote administration, secure command execution, and encrypted data transfers via SFTP or SCP as a secure alternative to Telnet (port 23).

Which of the following devices could be used to extend transmissions of a signal over longer distances by receiving and retransmitting a given signal at the lowest cost?

A repeater