---
title: "Short note: STP versus UTP"
subject: "Data Communication"
chapter: 4
key: "semester_5/data_communication:utp-vs-stp"
source: https://www.bctengineer.com/q/semester_5/data_communication/utp-vs-stp
site: BCT Engineering
---

# Short note: STP versus UTP

Data Communication · Chapter 4: Transmission Media

- Asked in: 2076 Chaitra, 4 marks; 2073 Chaitra, 5 marks (asked 2 times)
- Video: [Ethernet Cables, UTP vs STP, Straight vs Crossover, CAT 5,5e,6,7,8 Network Cables](https://www.youtube.com/watch?v=_NX99ad2FUA) — PowerCert Animated Videos
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/utp-vs-stp
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-4

## Question

Write a short note on STP versus UTP.

## Short answer

UTP cables have twisted pairs with only a plastic jacket, low cost, easy installation, but higher susceptibility to noise; they support up to 10 Gbps. STP adds a metallic shield around pairs for better noise immunity, higher cost, stiffer, requires grounding, and supports up to 10 Gbps+.

## Answer

**UTP (Unshielded Twisted Pair)** has pairs of insulated copper wires twisted together, with only a plastic jacket and no metallic shield. **STP (Shielded Twisted Pair)** has the same twisted pairs wrapped in a metal foil or braided shield (around each pair and/or the whole cable) before the jacket.

| Point | UTP | STP |
|---|---|---|
| Shielding | None | Metal foil / braid shield |
| Noise (EMI, crosstalk) | More susceptible | Much better immunity |
| Cost | Low | Higher |
| Size and weight | Thin, light, flexible | Thicker, heavier, stiffer |
| Installation | Easy | Harder; shield must be grounded |
| Attenuation | Higher at high frequency | Lower |
| Data rate | Up to 1 Gbps (Cat 5e) and 10 Gbps (Cat 6A) over 100 m | Higher, up to 10 Gbps+ (Cat 7) |
| Use | Ethernet LANs, telephone | Noisy factories, token ring, high-speed links |

UTP is the most widely used cable for LANs because of its low cost, while STP is chosen where interference is high.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. STP differs from UTP by
   A. More twists
   B. A metal foil/braid shield
   C. Thicker wire only
   D. No jacket
   Answer: B. Definition. (Key point: Shielding)

2. Noise immunity
   A. UTP better
   B. Equal
   C. STP better
   D. Neither
   Answer: C. Shield. (Key point: Noise)

3. UTP cost is
   A. Higher
   B. Equal
   C. Infinite
   D. Lower
   Answer: D. No shield. (Key point: Cost)

4. STP is used where
   A. Interference is high
   B. Low cost needed
   C. Short LANs
   D. Telephone
   Answer: A. Noisy environments. (Key point: Use)

## Related in Data Communication

- [Short note: Optical fiber versus STP](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aoptical-fiber-vs-stp) — Data Communication, chapter 4