CompTIA A+ 220-1101: Basic Cable Types, Connectors, Features, and Purposes

Honestly, cable identification is one of those A+ Core 1 topics that comes up all the time in the real world. You’ll run into it on desktops, switches, docks, printers, monitors, patch panels, storage gear — basically everywhere a technician turns around. On the exam, CompTIA usually doesn’t make this too fancy. Usually, they’ll show you a connector, mention a device, or describe a problem, and then they’re really just asking you to figure out the right cable, connector, or next troubleshooting step. In real support work, the same skill saves time. If you can quickly figure out what a cable is, what it carries, how far it can go, and which ports it fits, you’ll solve problems a whole lot faster.

For A+, I always tell people to learn every cable by asking five simple questions: what does it look like, what connector does it use, what devices does it connect, what features matter most, and when would a tech actually choose it? That method works way better than just memorizing names and hoping they stick.

A+ Core 1 Cable Objective: What You Must Know

The 220-1101 exam wants you to recognize the basic cable types and know what connectors they use, what features matter, and what they’re actually used for. If you’re running short on study time, these are the first high-value facts I’d really focus on:

• Ethernet over twisted pair commonly uses an 8P8C modular connector, commonly called RJ-45 on the exam.
• RJ-11 is smaller and used for phone/DSL lines.
• VGA is analog; HDMI and DisplayPort are digital.
• Cat 5e/Cat 6/Cat 6a are the main copper Ethernet categories to know.
• Standard twisted-pair Ethernet channel length is 100 meters total: typically 90 m permanent link + 10 m patch cords.
• Single-mode fiber is for longer distances; multimode is for shorter runs.
• USB-C is a connector shape, not a guarantee of speed, charging level, or video support.
• SATA data and SATA power are different connectors.

Core Cable Concepts Without the Fluff

A cable is the medium carrying data, video, audio, or power. A connector is the end attached to the cable. A port is the receptacle on the device. That distinction matters because exam questions often try to blur it.

Also, keep in mind that the shape of the connector doesn’t always tell you what the cable can actually do. A USB-C connector might support only charging, or charging plus USB 2.0 data, or high-speed data, or DisplayPort Alt Mode, or Thunderbolt — it all depends on the cable and the port. Same shape, but a totally different function depending on the setup.

Analog and digital matter too. Analog links like VGA can slowly get worse over distance or from noise, and that’s when you start seeing blur, ghosting, or weird color problems. Digital links like HDMI and DisplayPort usually avoid that kind of analog image degradation, but they can still fail in other ways — dropouts, sparkles, no signal, or unsupported display modes.

Twisted-Pair Copper Ethernet Cables are the bread-and-butter network cables you’ll see in almost every office environment.

Twisted-pair copper is the cable family I’ve seen most often in office networking, and honestly, it’s not even close. Twisted-pair cable uses copper wires twisted into pairs, and that twist isn’t just for looks — it helps cut down on crosstalk and interference. The two main types are UTP (unshielded twisted pair) and STP (shielded twisted pair). UTP is the everyday standard in offices. STP gets used when extra shielding is needed, but here’s the catch: shielding only helps if it’s installed and grounded properly.

Ethernet patch cables and horizontal cabling usually terminate in an 8P8C modular connector, commonly called RJ-45 in A+ study materials. Sure, use the exam shorthand if that helps, but don’t stop there — know the actual technical term too.

In the real world, twisted-pair Ethernet cables are everywhere — I’ve seen them in PCs, switches, routers, VoIP phones, printers, wireless access points, patch panels, and wall jacks more times than I can count. Ethernet can also carry power using PoE, which makes it important for access points, IP cameras, and phones.

Ethernet Category Quick Reference

For exam purposes, focus heavily on Cat 5e, Cat 6, and Cat 6a. If the question sounds like a normal office network run, Cat 5e or Cat 6 is probably your first best guess. If it mentions 10 Gb over longer copper distance, think Cat 6a. If it mentions very short, very high-speed data center links, that’s where Cat 8 starts to make sense.

T568A, T568B, straight-through, and crossover are the Ethernet termination terms that keep popping up again and again, both on the exam and out in the field.

Ethernet twisted-pair cabling can be terminated using T568A or T568B. Both standards are valid, so you’re not wrong just because you picked one over the other. What really matters is staying consistent from one end to the other. Most of the time, you want the same wiring standard on both ends unless you’re intentionally doing something different.

T568A pin order: white/green, green, white/orange, blue, white/blue, orange, white/brown, brown

T568B pin order: white/orange, orange, white/green, blue, white/blue, green, white/brown, brown

If both ends use the same standard, the cable is straight-through. If one end uses A and the other uses B, that creates a crossover cable. Back in the day, straight-through cables were used for different device types, like a PC to a switch, and crossover cables were used for similar devices, like switch to switch or PC to PC. That mattered a lot more in the old 10/100 Ethernet days, when transmit and receive pairs were tied to specific pins such as 1-2 and 3-6. On modern gear, auto-MDI/MDI-X usually makes crossover cables unnecessary.

A useful exam trap: a cable can pass simple continuity and still be badly terminated. A split pair may show the right pin numbers but poor performance because the pair twists were not kept correctly.

PoE Basics

Power over Ethernet lets Ethernet cabling deliver both network connectivity and power. Common powered devices include:

• VoIP phones are a classic PoE device.
• Wireless access points are another very common PoE-powered device.
• IP cameras
• Some badge readers and IoT devices

Know these standards at a recognition level:

• 802.3af — PoE
• 802.3at — PoE+
• 802.3bt — PoE++ / 4PPoE

If an exam question asks how an access point or IP phone gets power without a local adapter, PoE is almost always what they want you to pick. If a PoE device won’t power up, I’d start with the switch port or injector, check the cable for continuity, and then make sure the device isn’t asking for more power than the port can deliver.

Structured cabling, patch panels, jacks, MDFs, and IDFs are really the backbone of a clean, organized office cabling setup.

Structured cabling is the organized building cabling system. It includes wall jacks, horizontal cabling, patch panels, telecom closets, and backbone links. The demarcation point is where the service provider hands off connectivity to the customer. The MDF (main distribution frame) is the primary telecom room, and IDFs (intermediate distribution frames) serve other areas or floors.

Common parts:

• Patch panel — termination point for permanent cabling
• Keystone jack — modular jack snapped into wall plate or patch panel
• 110 block — common punch-down style for Ethernet cabling
• 66 block — more associated with older telecom/voice systems

A typical office path looks like this: device → patch cable → wall jack → horizontal cable → patch panel → patch cable → switch.

Good labeling matters. A practical label chain might be: CR-B-03 wall jack → patch panel port 27 → switch port 14. That lets you trace faults quickly. Keep labels useful but not overly revealing to unauthorized people.

Basic Termination and Installation Practices

For A+, you don’t need to become a full cabling installer, but you absolutely should understand the workflow.

• You want to keep those wire twists intact right up close to the termination point.
• Use the same standard on both ends unless you’re intentionally building a crossover cable.
• Don’t crush cable bundles. I usually prefer hook-and-loop straps over cranking down tight zip ties.
• Try to avoid sharp bends, and don’t yank on the cable with too much pull tension.
• If you can help it, don’t run data cabling tightly parallel to power lines.
• Use plenum, riser, or general-purpose jacket types based on the code requirements for the space.

Plenum cable is used in air-handling spaces when building code requires it. Riser cable is for vertical runs between floors. PVC/general-purpose cable is common in standard spaces. And that’s a code issue, not just a personal preference.

Coaxial Cabling is still around for a reason, even if you don’t see it as often as Ethernet.

Coax remains important for broadband, RF, television, CCTV, and some test environments. It has a center conductor, dielectric insulation, shielding, and outer jacket. The shielding gives it strong resistance to interference compared with many copper alternatives.

Common connectors:

• F-type — cable internet, cable TV, set-top boxes, DOCSIS modems
• BNC — CCTV, lab gear, test equipment, some legacy 10BASE2 contexts

Important coax facts:

• RG-6 is common for cable TV and cable internet.
• RG-59 is more legacy-oriented and common in older CCTV or shorter video runs.
• 75-75-ohm coax is common for TV and broadband, while 50-ohm coax is more common in some RF and test environments.
• Splitters reduce signal strength, so if you keep splitting the line too much, you can absolutely create service problems.

If a cable modem connects to provider service, the expected answer is usually coax with an F-type connector.

Fiber-optic cabling is the right call when distance, speed, or interference resistance really starts to become important.

Fiber sends data as light instead of electrical current, so EMI and RFI don’t bother it the way they do copper cabling. It’s the right choice when you need long distance, high speed, or electrical isolation between two points.

Common connectors include LC, SC, and ST. LC is small and very common on modern gear. SC is square push-pull. ST is older and bayonet-style.

Fiber links are often duplex, meaning one strand transmits and one receives. If TX and RX polarity are reversed, the link may stay down. That is a common troubleshooting point. Fiber also has bend-radius limits and must be kept clean. Dirty ferrules, damaged ends, or mismatched optics are common causes of no-link conditions.

SFP and SFP+ Modules

Fiber usually connects to a switch or router through a transceiver. The key terms are:

• SFP — commonly 1 Gb
• SFP+ — commonly 10 Gb

When selecting optics, both ends must match on:

• Speed
• You’ve also got to match the fiber type on both ends — single-mode to single-mode, or multimode to multimode.
• And don’t forget the transceivers: the optic type and wavelength have to match too, such as short-range modules on both ends or long-range modules on both ends.
• Connector format
• Duplex expectations and polarity

Example: a multimode LC uplink at 10 Gb usually needs matching SFP+ short-range optics and compatible multimode fiber on both ends. If one side uses single-mode long-range optics and the other side uses multimode short-range optics, the link’s going to fail.

USB and Peripheral Cables

USB is a major A+ topic because it is used for data, charging, and sometimes video. The biggest exam trap is assuming the connector shape tells you everything. Nope — not by itself.

Know some USB speed examples:

• USB 2.0 — 480 Mbps
• USB 3.2 Gen 1 — 5 Gbps
• USB 3.2 Gen 2 — 10 Gbps
• USB4 — higher throughput depending on implementation

Connector type does not define speed. A USB-C cable might only support USB 2.0 data, and honestly, that catches a lot of people off guard. Some cables are basically charge-only or low-data cables. Higher-power and higher-feature USB-C cables may use an e-marker chip so devices can identify cable capability.

USB-C, Alt Mode, and Thunderbolt are related, but they’re definitely not the same thing — and that’s where a lot of people get tripped up.

USB-C is the connector. USB 2.0 and 3.x are the data standards, not the connector shape.USB4 are protocol families. Thunderbolt 3 and 4 use the USB-C connector shape, but not every USB-C port is Thunderbolt. Earlier Thunderbolt versions used Mini DisplayPort connectors.rs instead of USB-C.

Video over USB-C usually depends on DisplayPort Alt Mode or Thunderbolt support. That means all three pieces may matter:

• The port must support the feature
• The cable must support the feature
• The dock/adapter must support the feature

If a laptop charges through a dock but external displays stay dark, suspect the USB-C cable first. A cable that can charge a device isn’t always a full-featured data or video cable.

Lightning is Apple-specific and still appears on some accessories and older devices, but many newer Apple devices, including recent iPhones and iPads, have transitioned to USB-C.

Video Display Cables and Adapters are one of those areas where connector shape and signal type both matter.

HDMI is often the easiest choice for TVs and shared presentation systems. DisplayPort is very common for desktop monitors and business workstations. That is an environment preference, not a rule that one is always technically superior for every use.

Adapter rule: passive adapters do not magically convert all signal types. A passive DVI-to-VGA adapter only works if the DVI source is carrying analog, like DVI-I or DVI-A. It won’t work from DVI-D. Likewise, some DisplayPort-to-HDMI conversions can be passive, while others need active conversion depending on the source and the target.

Internal Storage and Power Cabling

Inside a PC, you need to separate data cables from power cables.

• SATA data — 7-pin, connects motherboard to drive
• SATA power — 15-pin, comes from power supply to drive
• 4-pin peripheral power — commonly called Molex, legacy power connector
• PATA/IDE ribbon — 40-pin legacy data connector

SATA revisions are also worth recognizing:

• SATA I — 1.5 Gbps
• SATA II — 3 Gbps
• SATA III — 6 Gbps

PATA is legacy and uses a wide ribbon cable. It often supported two devices on one cable with master/slave jumper settings. If you see a wide flat ribbon in an exam image, your brain should jump straight to PATA or IDE.

Don’t confuse SATA power with PCIe GPU power or the motherboard 24-pin connector.in ATX connector. They serve different devices and are not interchangeable.

Legacy and Specialized Connectors

Serial console cables still matter in networking and infrastructure work. If a switch or firewall needs initial configuration through a console port, a serial connection or USB-to-serial adapter may be involved.

Most-Tested Look-Alikes

• RJ-45 vs RJ-11: RJ-45 is wider for Ethernet; RJ-11 is narrower for phone/DSL.
• USB-C vs Thunderbolt: same connector shape is possible, but Thunderbolt is a protocol capability, not just a shape.
• SATA data vs SATA power: SATA data is smaller 7-pin; SATA power is wider 15-pin.
• HDMI vs DisplayPort: both digital; HDMI is common on TVs, DP is common on PC monitors.
• Single-mode vs multimode fiber: single-mode for longer distance, multimode for shorter runs.

Troubleshooting Cables and Layer 1 Problems

Start with the physical layer before blaming software. A clean workflow is:

1. Verify the correct cable type for the job.
2. Check seating, latches, bent pins, cracked housings, and obvious damage.
3. Swap in a known-good cable.
4. Test the run with the right tool.
5. Then verify port configuration and device settings.

Useful tools:

• Wiremap/cable tester — checks opens, shorts, reversals, crossed pairs, and some miswires
• Continuity tester — basic conductor continuity only
• Certifier — validates installed cabling against performance standards; more advanced than a continuity tester
• Toner and probe — traces unknown copper runs; not for live network use in every situation and not for fiber
• Loopback plug — tests a port or interface path, such as NIC or serial troubleshooting
• Fiber inspection/cleaning tools — inspect ferrules and clean before insertion

Common fault patterns:

• Ethernet negotiates at 100 Mbps instead of 1 Gbps: often only two pairs are working, or there is a bad termination, damaged conductor, or split pair.
• Fiber link down: dirty connector, reversed polarity, wrong optic, wrong wavelength, wrong fiber type, or excessive bend.
• USB-C charges but no display: cable or port lacks Alt Mode or Thunderbolt support.
• No video through adapter: passive adapter mismatch or unsupported analog/digital conversion.

Three Fast Troubleshooting Scenarios

Scenario 1: Office desktop stuck at 100 Mbps. Likely issue: bad punch-down or only two pairs working. First step: test the copper run with a wiremap tester and inspect both terminations.

Scenario 2: Dock charges laptop but dual monitors do not work. Likely issue: USB-C cable or port does not support video. First step: replace with a known-good full-featured USB-C or Thunderbolt-compatible cable and verify the laptop port supports video output.

Scenario 3: Fiber uplink light is off after switch replacement. Likely issue: mismatched SFP/SFP+, wrong optic type, or reversed duplex strand order. First step: verify optic speed and type on both ends and swap TX/RX strands if appropriate.

Security and Physical Cable Handling

Cabling has security implications. Exposed patch panels, unlocked closets, and live unused ports create opportunities for rogue devices. Good practice includes:

• Locking telecom rooms and cabinets
• Disabling unused switch ports when possible
• Using clear but non-sensitive labels
• Watching for unauthorized patching or unknown devices
• Removing or properly disposing of retired cabling and labeled media

Exam Strategy and Final Cram Sheet

CompTIA likes questions that test recognition, not memorized trivia in isolation. Use these shortcuts:

• If you see a screw-on broadband cable, think F-type coax.
• If you see a square-ish printer connector, think USB-B.
• If you see a wide flat ribbon, think PATA/IDE.
• If you see a small paired fiber connector with a latch, think LC.
• If the question says longest distance, think fiber, usually single-mode.
• If the question says phone line, think RJ-11, not RJ-45.
• If the question says modern laptop dock, verify USB-C capability, not just shape.

Rapid review:

• Ethernet: 8P8C/RJ-45-style, Cat 5e/6/6a, 100 m channel, supports PoE.
• Coax: F-type for cable internet/TV, BNC for CCTV/test gear.
• Fiber: LC/SC/ST, single-mode long distance, multimode shorter distance, match optics carefully.
• USB: connector shape does not define speed or video support.
• Video: HDMI/DP digital, VGA analog, DVI variants matter.
• Storage: SATA data 7-pin, SATA power 15-pin, PATA is legacy ribbon.
• Legacy: DE-9 serial, DB-25 parallel, PS/2, eSATA, RJ-11.

The best way to study this topic is to connect the cable to the job. Ask what device it fits, what signal it carries, how far it can go, and what failure is most likely. That is how you answer A+ questions correctly, and it is exactly how a good technician thinks in the field.