CompTIA A+ 220-1201: 5th set of Videos

F connector

A threaded coax connector used for cable TV and DOCSIS modems.

Molex

Legacy 4-pin internal power connector (12V + 5V) using a friction-fit.

RJ11 vs. RJ45 Physical Compatibility

RJ11 fits into RJ45 ports because it is narrower, but RJ45 cannot fit into RJ11.

ST Connector

Straight Tip fiber connector using a twist (bayonet) locking mechanism.

SC Connector

Subscriber/Square/Standard Connector using a snap/click push-pull mechanism.

LC Connector

Lucent/Local/Little Connector; a small-form-factor fiber connector with a latch.

RAM vs. Storage Troubleshooting

Running out of 'memory' refers to RAM; running out of 'space' refers to storage.

DDR (Double Data Rate)

Memory technology that moves data on both the up and down clock cycles.

RAM Notch

A physical feature that prevents incorrect installation of different DDR generations.

Parity vs. ECC

Parity only detects errors; ECC detects and repairs errors (used in servers).

Even Parity Rule

The parity bit is set so the total count of 1s is an even number.

Dual-Channel Memory

Using two RAM sticks instead of one to roughly double memory bandwidth.

NVMe vs. AHCI

NVMe is designed for low-latency flash; AHCI is for slower spinning disks.

SATA 3 Throughput Limit

Maxes out at 6 Gbps, necessitating the move to PCIe and NVMe.

M.2 Keys (B and M)

B+M keyed drives are compatible with both B-key and M-key slots.

SAS (Serial Attached SCSI)

Enterprise-grade storage interface (~22.5 Gbps) designed for 24/7 high-load environments.

RAID 0 (Striping)

Splits data across 2+ drives for speed; has zero redundancy.

RAID 1 (Mirroring)

Duplicates data across 2+ drives for high redundancy; sacrifices 50% capacity.

RAID 5 (Striping with Parity)

Requires 3+ drives; uses parity to survive a single drive failure.

RAID 6 (Double Parity)

Requires 4+ drives; uses two parity blocks to survive two simultaneous drive failures.

RAID 10 (1+0)

A stripe of mirrors; requires 4+ drives and combines RAID 0 speed with RAID 1 redundancy.

Degraded State

A RAID array functioning with reduced protection/performance after a drive failure.

ATX (Advanced Technology Extended)

Largest common motherboard form factor; provides maximum expansion and RAM slots.

Micro-ATX

Medium form factor; shares ATX mounting points but has fewer expansion slots.

Mini-ITX

Smallest motherboard form factor; used for compact systems like HTPCs.

Motherboard Form Factor

The physical design standard determining dimensions, mounting, and component layout.