The answer is Network Address Translation (NAT), because it enables internet sharing for multiple devices on a private network by translating their internal private IP addresses into the single public IP assigned by the ISP. This process allows all internal devices to communicate with external servers through one connection, effectively conserving public IP addresses while providing internet access. On the CompTIA A+ Core 1 220-1201 exam, this concept tests your understanding of how a router bridges private and public networks; a common trap is confusing NAT with DHCP, which only assigns internal IPs and does not enable internet sharing, or with PAT, which is a specific form of NAT rather than the broad service. Remember the memory tip: NAT is the “bouncer” that lets your whole party (multiple devices) use one VIP pass (the public IP) to get into the club (the internet).
220-1201 Network Services Practice Question
This 220-1201 practice question tests your understanding of network services. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 has a single internet connection and needs to allow multiple internal devices to share that connection. The router's public IP is assigned by the ISP. Which network service must be enabled on the router to allow internal devices to communicate with external servers?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
NAT
NAT (Network Address Translation) allows multiple devices on a private network to share a single public IP address by translating their private IPs to the public IP. DHCP assigns internal IPs but does not enable internet sharing. DNS resolves names, and PAT is a form of NAT but not the broad service name.
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 internal devices, but it does not translate those addresses for internet access.
✗
DNS
Why it's wrong here
DNS resolves domain names to IP addresses, but it does not enable multiple devices to share a single public IP.
✓
NAT
Why this is correct
NAT translates private internal IP addresses to the router's public IP, allowing multiple devices to share the internet connection.
Related concept
Static NAT maps one inside address to one outside address.
✗
PAT
Why it's wrong here
PAT is a specific type of NAT that uses port numbers, but the general service required is NAT.
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: NAT — NAT (Network Address Translation) allows multiple devices on a private network to share a single public IP address by translating their private IPs to the public IP. DHCP assigns internal IPs but does not enable internet sharing. DNS resolves names, and PAT is a form of NAT but not the broad service name.
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.
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Question Discussion
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