easyMultiple ChoiceObjective-mapped
220-1201 Practice Question: A small office uses a single public IP address…
A small office uses a single public IP address for internet access. The network administrator wants internal web servers to be reachable from the internet on port 80. Which network service should be configured on the router to allow this?
⚠ Common exam trap
Test-takers frequently confuse DNS with port forwarding, thinking that DNS can direct traffic to internal servers, but DNS only resolves names to IP addresses and cannot change the destination port or translate private addresses.
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
✓
Port forwarding
Port forwarding (option B) is the correct answer because it allows the router to translate incoming traffic on a specific public IP address and port (e.g., TCP 80) to a specific internal private IP address and port of the web server. This is a form of Destination NAT (DNAT) that enables external hosts to reach internal services when only a single public IP is available.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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DHCP
Why it's wrong here
DHCP (Dynamic Host Configuration Protocol) is a network protocol primarily used to automatically assign unique IP addresses, subnet masks, default gateways, and DNS server information to client devices within a local area network (LAN). While essential for internal network management and device connectivity, it operates solely within the LAN segment and has no mechanism to direct or translate incoming external traffic from a public IP address to a specific internal server or service. Its function is internal address management, not external service exposure.
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Port forwarding
Why this is correct
Port forwarding, also known as Destination Network Address Translation (DNAT), is a technique used by routers to redirect communication requests from one address and port number combination to another while the packets are traversing a network gateway. In the context of a single public IP, it specifically allows external devices to initiate connections to a specific service running on a private IP address within the LAN by mapping an incoming public port to a designated internal IP address and its corresponding service port. This is the precise mechanism for exposing internal services to the internet when only one public IP is available.
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DNS
Why it's wrong here
DNS (Domain Name System) is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. Its primary role is to translate human-readable domain names (like example.com) into numerical IP addresses that computers use to identify each other. While crucial for locating a server by its IP, DNS itself does not handle the actual routing or redirection of network traffic based on port numbers, nor does it facilitate the translation of a public IP to a private IP for internal service access.
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VPN
Why it's wrong here
A VPN (Virtual Private Network) establishes a secure, encrypted connection (a "tunnel") over a less secure network, such as the internet, allowing remote users or networks to securely access resources on a private network as if they were directly connected. While VPNs provide secure remote access and can be used to access internal services *after* establishing the tunnel, their purpose is not to directly expose an internal service to the general public internet via a single public IP address. Instead, they provide a secure *path* for authorized users to reach internal resources.
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Related to this question
Learn chapter
Network Configuration: IP, DNS, DHCP
Key term
TCP
TCP (Transmission Control Protocol) is a core internet protocol that ensures data is sent reliably and in order between devices over a network.
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 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 220-1201 exam.