- A
DHCP
Why wrong: DHCP assigns IP addresses to devices on the LAN, but does not forward external traffic to internal servers.
- B
Port forwarding
Port forwarding maps an external port to an internal IP and port, enabling external access to internal services.
- C
DNS
Why wrong: DNS resolves domain names to IP addresses but does not redirect traffic to specific internal ports.
- D
VPN
Why wrong: VPN creates a secure tunnel for remote access but is not used for exposing internal services to the internet.
Question 315 of 1,020
Port Forwarding: How to Expose Internal Web Servers to the Internet
This 220-1201 practice question tests your understanding of network services. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Quick Answer
The correct answer is port forwarding, because it is the only network service that maps external requests on a specific port, such as port 80, to an internal private IP address and port behind a router using Network Address Translation (NAT). This configuration is essential when a small office has only one public IP and needs to expose internal web servers to the internet, as port forwarding creates a direct tunnel for inbound traffic while keeping the internal network hidden. On the CompTIA A+ Core 1 220-1201 exam, this question tests your understanding of how NAT and port forwarding work together to enable remote access; a common trap is confusing port forwarding with DHCP or DNS, which handle IP assignment and name resolution, not port-based redirection. To remember it, think of port forwarding as a “door number” on your router—you tell the router, “When someone knocks on door 80, send them to the server in room 192.168.1.10.”
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DHCP
Why it's wrong here
DHCP assigns IP addresses to devices on the LAN, but does not forward external traffic to internal servers.
- ✓
Port forwarding
Why this is correct
Port forwarding maps an external port to an internal IP and port, enabling external access to internal services.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
DNS
Why it's wrong here
DNS resolves domain names to IP addresses but does not redirect traffic to specific internal ports.
- ✗
VPN
Why it's wrong here
VPN creates a secure tunnel for remote access but is not used for exposing internal services to the internet.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often 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.
Detailed technical explanation
How to think about this question
Under the hood, port forwarding works by creating a static entry in the router's NAT table that maps a specific external IP:port combination to an internal IP:port. When a packet arrives at the router's WAN interface with destination port 80, the router rewrites the destination IP and port before forwarding the packet to the internal LAN. In real-world scenarios, if multiple internal servers need to be reachable on the same port (e.g., port 80), the administrator must use different external ports (e.g., 8080, 8081) or implement a reverse proxy to differentiate traffic.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
Visual reference
What to study next
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Network Services — This question tests Network Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
3 more ways this is tested on 220-1201
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 technician needs to configure a router to allow internal users to access a web server on the internet using a public IP address. The web server is hosted internally on a private IP. Which network service must be configured on the router?
medium- A.DNS
- B.DHCP
- ✓ C.NAT
- D.RADIUS
Why C: C is correct because Network Address Translation (NAT) translates the private IP address of the internal web server to a public IP address, allowing internal users to reach it over the internet. Without NAT, the router would drop packets with private source addresses destined for the internet, as private IPs are not routable on the public internet per RFC 1918.
Variation 2. A company's web server is hosted internally and must be accessible from the internet using the domain name www.company.com. The public IP address of the router is 203.0.113.5. Which two network services must be correctly configured to make this work?
medium- A.DNS and DHCP
- ✓ B.DNS and NAT
- C.NAT and ARP
- D.DHCP and NAT
Why B: DNS is required to resolve the domain name www.company.com to the public IP address 203.0.113.5, so external users can reach the router. NAT (specifically destination NAT or port forwarding) is needed to translate the public IP and port to the internal private IP address of the web server, allowing inbound traffic to reach the internal host.
Variation 3. A company's web server is accessible from the internet, but users report that the website loads slowly. The server's public IP is 203.0.113.10, and the internal IP is 192.168.1.10. The network administrator notices that the router's port forwarding rule is set to forward port 80 to 192.168.1.10:8080. What is the likely cause of the slow performance?
medium- A.The DNS server is misconfigured
- B.The NAT table is full
- ✓ C.The port forwarding rule uses the wrong internal port
- D.The DHCP scope is exhausted
Why C: Port forwarding should map external port 80 to the server's internal port 80, not 8080 unless the server listens on 8080. If the server listens on port 80, the mismatch causes connection delays or errors as the router forwards to a closed port. Correcting the internal port resolves the issue.
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Last reviewed: Jul 4, 2026
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