CCNA Network Services and Security Practice Question
A small office wants branch routers to automatically hand out IP addresses, default gateway values, and DNS servers to clients. Which service should be configured?
⚠ Common exam trap
A common exam trap is confusing DHCP with other network services like DNS, NTP, or TACACS+. DNS only resolves domain names to IP addresses and does not assign IP addresses or default gateways. NTP synchronizes time across devices but does not handle IP addressing. TACACS+ is an AAA protocol used for authentication and authorization, not for assigning IP addresses or network parameters. Selecting any of these instead of DHCP leads to incorrect answers because they do not fulfill the requirement of automatically handing out IP addresses and related network configuration to clients.
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 is built for this exact job. It centrally provides addressing details so endpoints do not need to be configured by hand.
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 (Domain Name System) resolves human-friendly hostnames such as example.com to numeric IP addresses through a hierarchical lookup process using UDP/TCP port 53. DNS servers are often assigned via DHCP, but DNS itself does not lease or allocate IP addresses to clients. A host must already have an IP address to query DNS, so it cannot hand out addressing.
When this WOULD be correct
If the question asked about a service that resolves domain names for clients in a network, such as 'Which service translates domain names into IP addresses for client devices?', then DNS would be the correct answer.
- ✓
DHCP
Why this is correct
DHCP automatically assigns IP addresses, subnet masks, default gateways, DNS servers, and other network parameters from a defined scope. This eliminates the need for manual static configuration, ensuring that each client receives valid, non-conflicting addressing. In a small office, the branch router can act as a DHCP server or BOOTP relay agent to dynamically hand out IPs to hosts.
- ✗
NTP
Why it's wrong here
NTP (Network Time Protocol) synchronizes clock time across network devices using UDP port 123, aligning timestamps for logs, authentication, and troubleshooting. It does not distribute any IP addressing or host configuration parameters; its sole function is time synchronization. Therefore, NTP cannot provide clients with IP addresses, subnet masks, or gateways.
When this WOULD be correct
In a scenario where the question asks about synchronizing time across devices in a network, such as ensuring that all routers and servers have the same time for logging and security purposes, NTP would be the correct answer.
- ✗
TACACS+
Why it's wrong here
TACACS+ (Terminal Access Controller Access-Control System Plus) is a Cisco AAA protocol that manages authentication, authorization, and accounting for administrative access to network devices over TCP port 49. It controls which administrators can log in and what commands they can run, but it is unrelated to client endpoint addressing. Hence, TACACS+ cannot assign IP parameters to hosts.
When this WOULD be correct
If the question asked about securing access to network devices and managing user permissions, then TACACS+ would be the correct answer. For example, a scenario might involve configuring user access controls for routers and switches in a corporate environment.
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 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓DHCPCorrect answer▾
Why this is correct
DHCP automatically assigns IP addresses, subnet masks, default gateways, DNS servers, and other network parameters from a defined scope. This eliminates the need for manual static configuration, ensuring that each client receives valid, non-conflicting addressing. In a small office, the branch router can act as a DHCP server or BOOTP relay agent to dynamically hand out IPs to hosts.
✗DNSWrong answer — click to see why▾
Why this is wrong here
DNS (Domain Name System) is responsible for resolving domain names to IP addresses, not for assigning IP addresses or providing gateway and DNS information to clients. Therefore, it cannot fulfill the requirements of the question.
★ When this WOULD be the correct answer
If the question asked about a service that resolves domain names for clients in a network, such as 'Which service translates domain names into IP addresses for client devices?', then DNS would be the correct answer.
Why candidates choose this
Candidates may confuse DNS with DHCP due to their roles in network configuration, thinking that both are involved in providing necessary information to clients, leading them to mistakenly select DNS.
✗NTPWrong answer — click to see why▾
Why this is wrong here
NTP (Network Time Protocol) is used to synchronize clocks across devices in a network, not for assigning IP addresses or providing gateway and DNS information to clients. Therefore, it does not fulfill the requirements of the question.
★ When this WOULD be the correct answer
In a scenario where the question asks about synchronizing time across devices in a network, such as ensuring that all routers and servers have the same time for logging and security purposes, NTP would be the correct answer.
Why candidates choose this
Candidates may confuse NTP with DHCP due to both being essential network services, leading them to mistakenly believe that NTP could also handle IP address assignment tasks.
✗TACACS+Wrong answer — click to see why▾
Why this is wrong here
TACACS+ is a protocol used for network device authentication, authorization, and accounting, not for assigning IP addresses or network configuration to clients. Therefore, it does not meet the requirements of the question.
★ When this WOULD be the correct answer
If the question asked about securing access to network devices and managing user permissions, then TACACS+ would be the correct answer. For example, a scenario might involve configuring user access controls for routers and switches in a corporate environment.
Why candidates choose this
Candidates might confuse TACACS+ with DHCP due to both being related to network management, leading them to mistakenly believe that TACACS+ could also handle IP address assignment tasks.
Analysis generated from the official 200-301blueprint 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
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
Go deeper
Related to this question
Learn chapter
Diagnosing DNS Record Issues — A, AAAA, CNAME, MX, NS, and PTR Records
Key term
DHCP
Dynamic Host Configuration Protocol (DHCP) automatically assigns IP addresses and network settings to devices on a network, so they can communicate without manual configuration.
Key term
Fully Qualified Domain Name
A Fully Qualified Domain Name is the complete and unambiguous website or server name that includes the host, domain, and top-level domain, leaving no room for guesswork.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco 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 200-301 exam.