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.”
220-1101 Network Services Practice Question
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?
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 allows external requests on a specific port to be redirected to an internal IP address and port. This is the standard method to make internal servers accessible from the internet when using NAT. Other options like DHCP or DNS do not handle port-based redirection.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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
Static NAT maps one inside address to one outside address.
✗
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: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 220-1201 NAT questions on configuration and troubleshooting.
Network Services — This question tests Network Services — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Port forwarding — Port forwarding allows external requests on a specific port to be redirected to an internal IP address and port. This is the standard method to make internal servers accessible from the internet when using NAT. Other options like DHCP or DNS do not handle port-based redirection.
What should I do if I get this 220-1201 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related 220-1201 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
About these practice questions
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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: This question tests knowledge of NAT. Network Address Translation (NAT) translates private IPs to public IPs and vice versa, enabling internal servers to be reachable from the internet. DNS resolves names, but NAT handles the IP translation.
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 must resolve the domain name to the public IP, and NAT (specifically port forwarding) must translate that public IP to the internal web server's private IP. DHCP and ARP are not directly involved in internet-facing access.
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.
Last reviewed: Jun 18, 2026
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