CCNA Network Services and Security Practice Question
Which protocol is most directly responsible for keeping device clocks synchronized across a network?
⚠ Common exam trap
A frequent exam trap is selecting DHCP, TFTP, or CDP as the protocol responsible for clock synchronization. DHCP is often confused because it deals with network configuration, but it does not synchronize time. TFTP might seem relevant due to its role in transferring files like configurations, but it has no time-related function. CDP is a Cisco proprietary protocol for device discovery and neighbor information exchange, not for time services. Candidates must recognize that only NTP is designed specifically to keep device clocks synchronized across a network, which is critical for accurate logging and event correlation.
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
✓
NTP
The correct protocol is NTP. In plain language, NTP helps devices agree on the current time so that logs, authentication events, monitoring data, and troubleshooting records line up accurately. Without consistent time, a network team may see events from multiple devices but be unable to reconstruct the actual sequence correctly. This matters more than many people realize because accurate time underpins many operational workflows. Syslog messages, security events, and monitoring alerts become much easier to trust when devices are synchronized. DHCP, TFTP, and CDP are useful for other purposes, but they do not exist to align device clocks. NTP is the protocol specifically associated with time synchronization.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
NTP
Why this is correct
NTP (Network Time Protocol) is the correct answer because it is the industry-standard protocol designed specifically to synchronize device clocks across a network. It uses a hierarchical stratum system to distribute accurate time from authoritative time sources, typically over UDP port 123, ensuring consistent timestamps for syslogs, authentication, and network troubleshooting. Without NTP, event logs and monitoring data from different devices cannot be reliably correlated.
- ✗
TFTP
Why it's wrong here
TFTP (Trivial File Transfer Protocol) is incorrect because it is a lightweight file transfer mechanism used to copy configuration files and IOS images to network devices, typically over UDP port 69. It lacks the precision timing and time-source hierarchy necessary for clock synchronization, and it has no concept of time-stamping or adjusting device clocks. Thus, it is unrelated to keeping a device's time accurate.
When this WOULD be correct
If the question were to ask which protocol is used for transferring files in a network environment, especially in scenarios where minimal overhead is desired, TFTP would be the correct answer. This could involve a question about lightweight file transfer methods in embedded systems.
- ✗
DHCP
Why it's wrong here
DHCP (Dynamic Host Configuration Protocol) is incorrect because its primary role is to automatically assign IP addresses, subnet masks, default gateways, and DNS servers to clients, not to maintain time synchronization. Although DHCP can optionally deliver an NTP server address to clients via option 42, the protocol itself does not adjust or discipline any clock; it merely provides configuration parameters. Time synchronization remains the separate function of NTP.
When this WOULD be correct
In a question asking which protocol is responsible for providing network configuration settings, including IP addresses, subnet masks, and default gateways, DHCP would be the correct answer. For example, a question could ask about the protocol that dynamically assigns IP addresses to devices in a local area network.
- ✗
CDP
Why it's wrong here
CDP (Cisco Discovery Protocol) is incorrect because it is a proprietary Layer 2 neighbor discovery protocol that runs on Cisco devices to advertise their presence, hostname, IP address, platform, and capabilities to directly connected peers. It sends periodic multicast updates to learn about adjacent devices for network mapping and troubleshooting, but it does not carry time information or perform clock sync. Therefore, it cannot be responsible for device time synchronization.
When this WOULD be correct
If the exam question asked which protocol is used for discovering and sharing information about network devices, particularly in a Cisco environment, then CDP would be the correct answer, as it facilitates device identification and topology mapping.
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.
✓NTPCorrect answer▾
Why this is correct
NTP (Network Time Protocol) is the correct answer because it is the industry-standard protocol designed specifically to synchronize device clocks across a network. It uses a hierarchical stratum system to distribute accurate time from authoritative time sources, typically over UDP port 123, ensuring consistent timestamps for syslogs, authentication, and network troubleshooting. Without NTP, event logs and monitoring data from different devices cannot be reliably correlated.
✗TFTPWrong answer — click to see why▾
Why this is wrong here
TFTP is a lightweight file transfer protocol used for transferring configuration files and firmware images, typically for network device booting or backup. It does not provide any time synchronization functionality.
★ When this WOULD be the correct answer
If the question were to ask which protocol is used for transferring files in a network environment, especially in scenarios where minimal overhead is desired, TFTP would be the correct answer. This could involve a question about lightweight file transfer methods in embedded systems.
Why candidates choose this
Students may confuse TFTP with NTP due to the similar acronyms (both end in 'TP') and the fact that both are UDP-based protocols. However, their purposes are entirely different.
✗DHCPWrong answer — click to see why▾
Why this is wrong here
DHCP primarily assigns IP addresses, subnet masks, default gateways, and other network configuration parameters to clients. While DHCP can optionally provide an NTP server address via option 42, it does not itself synchronize clocks.
★ When this WOULD be the correct answer
In a question asking which protocol is responsible for providing network configuration settings, including IP addresses, subnet masks, and default gateways, DHCP would be the correct answer. For example, a question could ask about the protocol that dynamically assigns IP addresses to devices in a local area network.
Why candidates choose this
Because DHCP can offer an NTP server address, some students might think DHCP directly synchronizes clocks. However, the actual synchronization is performed by NTP, not DHCP.
✗CDPWrong answer — click to see why▾
Why this is wrong here
CDP is a Cisco proprietary Layer 2 protocol used for discovering directly connected Cisco devices, including device type, IP address, and platform. It has no role in time synchronization.
★ When this WOULD be the correct answer
If the exam question asked which protocol is used for discovering and sharing information about network devices, particularly in a Cisco environment, then CDP would be the correct answer, as it facilitates device identification and topology mapping.
Why candidates choose this
Students might confuse CDP with NTP because both are commonly used in Cisco networks and both involve device communication. However, CDP is for neighbor discovery, not time sync.
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?”
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Related to this question
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Device File Management with SFTP and SCP
Key term
Trivial File Transfer Protocol
TFTP is a simple, lightweight protocol used to transfer files between devices on a network without the security and error-checking features of more robust file transfer methods.
Key term
Precision Time Protocol
Precision Time Protocol is a network protocol used to synchronize clocks across devices with extremely high accuracy, often within microseconds or nanoseconds.
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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.