Display connectors are one of the most commonly tested topics on CompTIA A+ 220-1101. You must be able to identify HDMI, DisplayPort, DVI, VGA, and Thunderbolt display interfaces — their pin counts, capabilities, and when to use each. This guide covers every display connector in the A+ objectives.
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HDMI carries both digital video and audio over a single cable. Connector types: Type A (standard, 19-pin), Type C (Mini HDMI, 19-pin smaller), Type D (Micro HDMI, 19-pin smallest). Versions: HDMI 1.4 — 4K at 30Hz, 3D, Audio Return Channel (ARC). HDMI 2.0 — 4K at 60Hz, 18 Gbps bandwidth. HDMI 2.1 — 8K at 60Hz, 4K at 120Hz, 48 Gbps, eARC (Enhanced Audio Return Channel), Variable Refresh Rate. HDMI CEC (Consumer Electronics Control): allows one remote to control multiple HDMI-connected devices. ARC/eARC: sends audio from TV back to soundbar/receiver through the HDMI cable (eliminates separate audio cable). HDCP (High-bandwidth Digital Content Protection): DRM on HDMI — required to play protected content (Blu-ray, streaming).
DisplayPort (DP) is designed primarily for computers and monitors. Standard connector: rectangular with one angled corner (not rectangular like HDMI). Mini DisplayPort (mDP): smaller version used on older Macs and Thunderbolt 1/2. Versions: DisplayPort 1.2 — 4K at 60Hz, 21.6 Gbps, daisy-chaining up to 3 monitors via MST (Multi-Stream Transport). DisplayPort 1.4 — 8K at 60Hz, HDR, 32.4 Gbps. DisplayPort 2.0/2.1 — 16K, 77 Gbps. Supports audio. Daisy-chaining: connect monitor to PC, then second monitor to first monitor's DP out (monitor must support MST hub). Adaptive Sync / G-Sync / FreeSync: variable refresh rate protocols — require DisplayPort (or HDMI 2.1). Active adapters: DP to HDMI or DP to DVI require active adapters for some configurations.
DVI was the transition connector from analog VGA to digital displays. DVI types: DVI-D (digital only — most common), DVI-A (analog only), DVI-I (integrated — both digital and analog). DVI connector configurations: Single Link: up to 1920×1200 at 60Hz. Dual Link: up to 2560×1600 at 60Hz (wider connector with extra pins in center). DVI-D single link: 18+1 pins. DVI-D dual link: 24+1 pins. DVI-I single link: 18+5 pins (the +5 carries analog). DVI-I dual link: 24+5 pins. Identifying tip: DVI-D has a flat blade; DVI-A and DVI-I have a flat blade plus 4 surrounding pins. DVI does not carry audio. Largely replaced by HDMI and DisplayPort in modern hardware but common on older monitors and graphics cards.
VGA (DE-15 connector) is a legacy analog video interface. 15-pin, 3-row D-sub connector. Blue color-coding is common. Maximum practical resolution: 1920×1080 at 60Hz (image quality degrades significantly at high resolutions due to analog signal). No audio. No digital signal — analog means image quality is affected by cable quality and length. Still found on: older projectors, older monitors, KVM switches, legacy PCs. When an adapter from digital (HDMI/DP) to VGA is needed, an active adapter/converter is required (digital-to-analog conversion). VGA is officially deprecated and no longer included on most modern graphics cards and laptops. Identifying tip: 3 rows of 5 pins each, blue color, trapezoidal D-sub shell.
Thunderbolt 3 and 4 (USB-C connector): support up to two 4K displays or one 8K display simultaneously. Thunderbolt 3 supports DisplayPort 1.2; Thunderbolt 4 requires DisplayPort 1.4 or 2.0. Thunderbolt 1 and 2 (Mini DisplayPort connector): Thunderbolt 1 supports up to 2560×1440. Thunderbolt 2 supports 4K. USB4 (USB-C): also supports DisplayPort Alt Mode — can output video. USB-C DisplayPort Alt Mode: many USB-C ports (not Thunderbolt) support DisplayPort output via Alt Mode. Requires cable that supports Alt Mode or DP-to-USB-C adapter. Identifying tip: USB-C port with Thunderbolt outputs lightning bolt icon + monitor icon.
Passive adapters (no conversion electronics): work for same-signal conversions. HDMI to DVI-D: passive adapter works (both digital, no audio on DVI). DisplayPort to HDMI: may need active adapter depending on GPU. DVI-A to VGA: passive (both analog). Active adapters (contain conversion electronics): required for digital-to-analog. HDMI to VGA: requires active adapter. DisplayPort to VGA: requires active adapter. Single-link vs dual-link DVI matters when adapting — dual-link supports higher resolutions. USB-C to HDMI/DP: usually passive if the USB-C port supports Alt Mode. KVM switches: allow one keyboard/video/mouse set to control multiple computers — important to match the video connector type. Resolution and refresh rate may be limited by the weakest link in the chain (cable, adapter, monitor, GPU).
These questions are representative of what you will see on A+ exams. The correct answer and explanation are shown immediately below each question.
A technician needs to connect a modern laptop with only HDMI output to a projector with only VGA input. What is required?
Explanation: HDMI outputs a digital signal; VGA requires an analog signal. Converting between them requires an active adapter with digital-to-analog conversion circuitry, often powered via USB or an included power cable.
DisplayPort or HDMI 2.0+ are the best choices for modern monitors. Both are digital and capable of 4K/8K with high refresh rates. For gaming monitors, DisplayPort is preferred because it supports G-Sync/FreeSync and higher refresh rates. For TVs, HDMI is standard. VGA and DVI are legacy and should be avoided when digital alternatives exist.
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