Switch vs Hub: Which Device Expands a LAN Segment?
A company has a router with four Ethernet ports. They need to connect 12 wired devices in the same LAN segment. All devices must receive IP addresses from the same DHCP server running on the router. Which device should the technician add?
Quick Answer
The answer is a switch, because it is the correct device for expanding a LAN segment while keeping all connected devices in the same broadcast domain. A switch operates at Layer 2 of the OSI model, forwarding Ethernet frames based on MAC addresses, which allows it to handle DHCP broadcast traffic from the router transparently. This means all 12 wired devices can receive IP addresses from the router’s DHCP server without needing additional router ports. On the CompTIA A+ Core 1 220-1101 exam, this question tests your understanding of how switches extend a network versus hubs, which simply repeat signals and create more collisions. A common trap is choosing a hub because it costs less, but hubs operate at Layer 1 and cannot isolate traffic, leading to poor performance. Remember the memory tip: “Switches are smart, hubs are dumb”—switches learn MAC addresses, hubs just shout.
⚠ Common exam trap
Candidates often confuse a hub with a switch, thinking both simply 'split' a connection, but the CompTIA 220-1101 exam tests the understanding that a switch provides dedicated bandwidth and collision domains, while a hub does not, making the switch the only viable choice for multiple wired devices in a single LAN segment.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Switch
A switch is the correct device because it operates at Layer 2 of the OSI model, forwarding Ethernet frames based on MAC addresses, and can connect multiple devices while keeping them in the same broadcast domain. With four router ports already in use, adding a switch allows the 12 wired devices to share a single LAN segment and receive IP addresses from the router's DHCP server, as the switch transparently forwards DHCP broadcast traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Switch
Why this is correct
A switch forwards frames by MAC address within one broadcast domain, so all 12 devices share the router's single DHCP scope. Its multiple ports overcome the router's four-port limit without creating separate subnets, satisfying the requirement that every device obtain an address from the same DHCP server.
- ✗
Hub
Why it's wrong here
A hub repeats frames across all ports in one collision domain, so 12 devices share bandwidth and suffer collisions; a switch segments traffic. It is tempting as a cheap port multiplier, and would be correct only for legacy low-traffic or troubleshooting captures, not a production LAN segment.
When this WOULD be correct
A hub would be correct if the question specified a small network with very few devices (e.g., 2-3) and cost was the primary concern, or if the goal was to monitor traffic for troubleshooting in a low-traffic environment.
- ✗
Access point
Why it's wrong here
An access point bridges wireless clients onto the LAN; it adds no wired Ethernet ports for the 12 devices. It is tempting because it extends connectivity to more clients, and would be correct when devices connect over Wi-Fi, not when they require physical RJ45 connections to the router's DHCP.
When this WOULD be correct
A technician needs to extend wireless coverage to a new area where wired connections are unavailable; adding an access point connected to the router via Ethernet provides Wi-Fi access for wireless devices.
- ✗
Modem
Why it's wrong here
A modem converts between the ISP's WAN medium and Ethernet, providing no additional LAN switch ports and no DHCP relay. It is tempting as the device linking the network to the internet, and would be correct when the router lacks an integrated modem for the broadband line, not for expanding wired ports.
When this WOULD be correct
A technician needs to provide internet connectivity to a small office where the ISP requires a separate modem. The router lacks a built-in modem, so an external modem must be added between the ISP line and the router's WAN port.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓SwitchCorrect answer▾
Why this is correct
A switch forwards frames by MAC address within one broadcast domain, so all 12 devices share the router's single DHCP scope. Its multiple ports overcome the router's four-port limit without creating separate subnets, satisfying the requirement that every device obtain an address from the same DHCP server.
✗HubWrong answer — click to see why▾
Why this is wrong here
A hub operates at Layer 1 and cannot segment collision domains; with 12 devices, collisions would severely degrade performance, and the router's DHCP server would still work but inefficiently.
★ When this WOULD be the correct answer
A hub would be correct if the question specified a small network with very few devices (e.g., 2-3) and cost was the primary concern, or if the goal was to monitor traffic for troubleshooting in a low-traffic environment.
Why candidates choose this
Candidates may confuse hubs with switches, thinking both simply 'split' a connection, or they may recall that hubs are cheaper and assume they suffice for basic connectivity.
✗Access pointWrong answer — click to see why▾
Why this is wrong here
An access point provides wireless connectivity but does not add wired Ethernet ports; the router already has only four ports, so an access point would not allow connecting 12 wired devices.
★ When this WOULD be the correct answer
A technician needs to extend wireless coverage to a new area where wired connections are unavailable; adding an access point connected to the router via Ethernet provides Wi-Fi access for wireless devices.
Why candidates choose this
Candidates may confuse 'access point' with 'switch' or think it can serve as a hub for wired devices, misunderstanding that access points primarily bridge wireless clients to the wired network.
✗ModemWrong answer — click to see why▾
Why this is wrong here
A modem is used to connect a LAN to a WAN (e.g., internet), not to expand the number of wired devices in a LAN. The router already has a modem function or connects to one; adding another modem does not increase Ethernet ports for local devices.
★ When this WOULD be the correct answer
A technician needs to provide internet connectivity to a small office where the ISP requires a separate modem. The router lacks a built-in modem, so an external modem must be added between the ISP line and the router's WAN port.
Why candidates choose this
Candidates may confuse a modem with a switch or hub, thinking it provides additional network ports for devices, or they may assume that any networking device can extend a LAN.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
Go deeper
Related to this question
About these practice questions
One of 896 original 220-1101 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
2 more ways this is tested on 220-1101
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A small office has 18 computers that need to be connected to share files and access the internet. The ISP provides a modem with a single Ethernet port. The office router has four LAN ports. Which device should the technician add to enable all 18 computers to connect to the network?
medium- A.A. A hub
- ✓ B.B. A switch
- C.C. A bridge
- D.D. A firewall
Why B: A switch is the correct device because it provides multiple Ethernet ports (typically 24 or 48) and operates at Layer 2, forwarding frames based on MAC addresses. This allows all 18 computers to connect to the network, share files, and access the internet through the existing router, which only has four LAN ports.
Variation 2. A technician is setting up a small office network with 20 computers. The ISP provides a modem that only has one Ethernet port. The technician needs to connect all computers to the internet and allow them to communicate with each other. Which device should the technician use to connect the computers to the modem?
medium- A.A hub
- B.A bridge
- ✓ C.A switch
- D.A router
Why C: A switch is the correct device because it operates at Layer 2 of the OSI model, using MAC addresses to forward frames only to the specific port where the destination device is connected. This allows all 20 computers to communicate with each other locally and share the single Ethernet port from the modem for internet access, while providing dedicated bandwidth per port and reducing collisions.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.