220-1101 Networking Practice Question
A technician is setting up a small office network. The ISP provides a modem with a single Ethernet port. The office has 10 computers that all need to share the single public IP address to access the internet. Which of the following devices should the technician connect directly to the modem to allow all computers to access the internet?
⚠ Common exam trap
Test-takers frequently confuse a switch or hub with a router, mistakenly thinking that any device with multiple ports can share an internet connection, but only a router can perform NAT to translate private addresses to a single public IP.
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
✓
Router
A router is required to perform Network Address Translation (NAT), which allows multiple devices on a local network to share a single public IP address provided by the ISP's modem. The router connects directly to the modem's Ethernet port and then distributes private IP addresses (e.g., 192.168.x.x) to the 10 computers, translating their outbound traffic to the single public IP. A switch or hub alone cannot perform NAT and would not enable internet sharing without a router.
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 it's wrong here
A switch forwards Ethernet frames by MAC address within a LAN and cannot translate the single public IP for ten hosts. It is tempting because switches connect multiple computers, but sharing one public address requires NAT and DHCP, functions performed by a router placed directly behind the modem.
When this WOULD be correct
A technician is setting up a small office network where the ISP provides a modem with a built-in router that already performs NAT and DHCP. The office has 10 computers that need to be connected to the same local network. In this case, a switch connected directly to the modem would allow all computers to communicate locally and access the internet via the modem's routing capabilities.
- ✓
Router
Why this is correct
A router performs NAT, translating the single public IP address across the ten private hosts, and provides DHCP and switching. A modem alone cannot share one address, and a switch or access point lacks the routing and NAT functions the scenario requires.
- ✗
Hub
Why it's wrong here
A hub repeats every frame to all ports and cannot perform NAT, so it cannot share one public IP address across ten computers. It is tempting as a cheap way to link multiple devices, and would be correct for extending a single collision domain, not for internet sharing.
When this WOULD be correct
If the ISP provided multiple public IP addresses and the modem had a built-in router or the network required only local connectivity without internet sharing, a switch would be correct to extend the network.
- ✗
Bridge
Why it's wrong here
A bridge forwards frames within one subnet by MAC address and performs no NAT, so ten hosts cannot share the single public IP. It is tempting because bridges join network segments, but the requirement is address translation and DHCP, which a router provides when connected directly to the modem.
When this WOULD be correct
In a scenario where the ISP provides multiple public IP addresses (e.g., a /29 subnet) and each computer needs a unique public IP, a switch connected to the modem would allow all computers to use their own public IPs directly.
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.
✓RouterCorrect answer▾
Why this is correct
A router performs NAT, translating the single public IP address across the ten private hosts, and provides DHCP and switching. A modem alone cannot share one address, and a switch or access point lacks the routing and NAT functions the scenario requires.
✗SwitchWrong answer — click to see why▾
Why this is wrong here
A switch cannot perform Network Address Translation (NAT) or routing; it only forwards frames within the same subnet. With only one public IP from the modem, a switch would not allow 10 computers to share that IP to access the internet.
★ When this WOULD be the correct answer
A technician is setting up a small office network where the ISP provides a modem with a built-in router that already performs NAT and DHCP. The office has 10 computers that need to be connected to the same local network. In this case, a switch connected directly to the modem would allow all computers to communicate locally and access the internet via the modem's routing capabilities.
Why candidates choose this
Candidates may confuse a switch with a router, thinking that a switch can provide internet access to multiple devices, or they may assume that the modem already handles routing and NAT, which is not specified in this question.
✗HubWrong answer — click to see why▾
Why this is wrong here
A switch operates at Layer 2 and cannot perform NAT or routing; connecting a switch directly to the modem would only allow one computer to obtain the public IP, leaving the others without internet access.
★ When this WOULD be the correct answer
If the ISP provided multiple public IP addresses and the modem had a built-in router or the network required only local connectivity without internet sharing, a switch would be correct to extend the network.
Why candidates choose this
Candidates may think a switch is sufficient to share the internet connection because it connects multiple devices, overlooking the need for NAT/routing to share a single public IP.
✗BridgeWrong answer — click to see why▾
Why this is wrong here
A switch operates at Layer 2 and cannot perform NAT or PAT, so it cannot share a single public IP address among multiple devices. Connecting a switch directly to the modem would only allow one computer to obtain the public IP, leaving the rest without internet access.
★ When this WOULD be the correct answer
In a scenario where the ISP provides multiple public IP addresses (e.g., a /29 subnet) and each computer needs a unique public IP, a switch connected to the modem would allow all computers to use their own public IPs directly.
Why candidates choose this
Candidates may confuse a switch with a router, assuming that a switch can handle IP address sharing because it connects multiple devices, but they overlook the need for Network Address Translation (NAT).
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?”
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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.