What Protocol Automatically Assigns IP Addresses and Provides Subnet Mask and Default Gateway?
Which of the following protocols is used to automatically assign IP addresses to devices on a network and also provides the subnet mask and default gateway?
Quick Answer
DHCP is correct because the question is describing its complete core function: not just assigning an IP address, but also delivering the surrounding configuration a device needs to actually communicate on the network, including the subnet mask and default gateway. This happens through an exchange where a client broadcasts a discovery message and the server responds with an offer bundling all of these values together, so the device leaves the exchange fully configured without any manual input from a user or administrator. That combination - automatic address assignment plus subnet mask and gateway delivery in a single exchange - is specific enough to rule out protocols that only handle name resolution or only handle address translation, since neither of those hands out a complete network configuration. It's this bundling of multiple configuration parameters in one automated exchange that makes DHCP so central to how modern networks operate, since manually configuring these values on every device would be impractical at scale. When an exam question describes a protocol that automatically hands a device its IP address along with additional configuration details like the subnet mask or gateway, rather than just one isolated piece of information, that combination is the signal pointing specifically to DHCP.
⚠ Common exam trap
The N10-009 exam often tests the distinction between DHCP and DNS, where candidates mistakenly think DNS assigns IP addresses because it 'looks up' information, but DNS only resolves names, not addresses or subnet masks.
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
✓
DHCP
DHCP (Dynamic Host Configuration Protocol) is the correct answer because it is specifically designed to automatically assign IP addresses to devices on a network, along with essential configuration parameters such as the subnet mask and default gateway. When a DHCP client sends a discover message, the DHCP server responds with an offer that includes these details, allowing the client to fully participate in network communication without manual configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DNS
Why it's wrong here
DNS translates domain names to IP addresses, not assign IPs.
When this WOULD be correct
A question asking which protocol translates human-readable domain names (like www.example.com) into IP addresses would have DNS as the correct answer.
- ✓
DHCP
Why this is correct
DHCP provides automatic IP configuration including subnet mask and default gateway.
- ✗
ARP
Why it's wrong here
ARP resolves IP addresses to MAC addresses on a local network.
When this WOULD be correct
A question asking 'Which protocol maps a known IP address to a MAC address on a local network?' would have ARP as the correct answer.
- ✗
ICMP
Why it's wrong here
ICMP is used for error reporting and diagnostics like ping.
When this WOULD be correct
A question asking which protocol is used to test connectivity between devices or to report network errors (e.g., 'Which protocol does the ping command use?') would have ICMP as the correct answer.
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 N10-009 exam frequently reuses these exact scenarios with slightly different constraints.
✓DHCPCorrect answer▾
Why this is correct
DHCP provides automatic IP configuration including subnet mask and default gateway.
✗DNSWrong answer — click to see why▾
Why this is wrong here
DNS resolves domain names to IP addresses, but does not assign IP addresses or provide subnet masks and default gateways.
★ When this WOULD be the correct answer
A question asking which protocol translates human-readable domain names (like www.example.com) into IP addresses would have DNS as the correct answer.
Why candidates choose this
Candidates may confuse DNS with DHCP because both involve IP addresses, but DNS is for name resolution, not automatic assignment.
✗ARPWrong answer — click to see why▾
Why this is wrong here
ARP (Address Resolution Protocol) is used to resolve IP addresses to MAC addresses on a local network, not to assign IP addresses or provide subnet masks and default gateways.
★ When this WOULD be the correct answer
A question asking 'Which protocol maps a known IP address to a MAC address on a local network?' would have ARP as the correct answer.
Why candidates choose this
Candidates may confuse ARP with DHCP because both operate at the network layer and are involved in network configuration, but ARP's role is address resolution, not assignment.
✗ICMPWrong answer — click to see why▾
Why this is wrong here
ICMP is used for network diagnostics and error reporting (e.g., ping, traceroute), not for automatic IP address assignment or providing subnet mask and default gateway.
★ When this WOULD be the correct answer
A question asking which protocol is used to test connectivity between devices or to report network errors (e.g., 'Which protocol does the ping command use?') would have ICMP as the correct answer.
Why candidates choose this
Candidates may confuse ICMP with DHCP because both are network-layer protocols, or they might think ICMP handles address configuration due to its role in network discovery tools.
Analysis generated from the official N10-009blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
IPv4 Address Class Summary
| Class | First Octet Range | Default Mask | Networks | Hosts per Network |
|---|---|---|---|---|
| A | 1–126 | /8 (255.0.0.0) | 126 | 16,777,214 |
| B | 128–191 | /16 (255.255.0.0) | 16,384 | 65,534 |
| C | 192–223 | /24 (255.255.255.0) | 2,097,152 | 254 |
| D | 224–239 | N/A | Multicast groups | — |
| E | 240–255 | N/A | Reserved / experimental | — |
127.x.x.x is reserved for loopback. Modern networks use CIDR (classless) rather than classful addressing.
Go deeper
Related to this question
Learn chapter
Interior vs Exterior Routing Protocols
Key term
Default gateway
A default gateway is a network device, typically a router, that acts as the exit point for traffic from a local network to other networks, including the internet.
Key term
Subnet mask
A subnet mask is a 32-bit number that helps a computer or network device determine which part of an IP address identifies the network and which part identifies the host device on that network.
About these practice questions
This N10-009 question is part of Courseiva's 464-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on N10-009
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. Which of the following protocols is used to automatically assign IP addresses to devices on a network?
easy- A.A) DNS
- ✓ B.B) DHCP
- C.C) ARP
- D.D) ICMP
Why B: DHCP (Dynamic Host Configuration Protocol) is the correct answer because it is specifically designed to automatically assign IP addresses and other network configuration parameters (such as subnet mask, default gateway, and DNS servers) to devices on a network. When a client device connects, it sends a DHCP Discover broadcast, and the DHCP server responds with an Offer, followed by a Request and Acknowledgment (DORA process), enabling plug-and-play connectivity.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This N10-009 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 N10-009 exam.