Question 285 of 1,819
Network Services and SecuritymediumMultiple SelectObjective-mapped

Quick Answer

The answer is that DHCP snooping validates DHCP client MAC addresses against the source MAC in the Ethernet frame, prevents DHCP starvation attacks by rate-limiting messages on untrusted ports, and builds a binding database to track valid IP-to-MAC assignments. These three characteristics are correct because DHCP snooping acts as a security filter between untrusted ports (facing clients) and trusted ports (facing DHCP servers), ensuring only legitimate DHCP traffic is processed. On the CCNA 200-301 v2 exam, this topic tests your understanding of how to mitigate spoofing and resource exhaustion attacks at Layer 2, often appearing in a multiple-select format where you must distinguish these core functions from features like DHCP relay or dynamic ARP inspection. A common trap is confusing DHCP snooping’s MAC validation with DAI’s ARP validation, so remember that snooping checks the source MAC in the Ethernet frame against the client’s hardware address in the DHCP packet. Memory tip: think “Snooping Sniffs Source MACs and Stops Starvation.”

CCNA Network Services and Security Practice Question

This 200-301 practice question tests your understanding of network services and security. 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.

Which three of the following are characteristics of DHCP snooping? (Choose three.)

Question 1mediummulti select
Read the full DHCP explanation →

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

It builds and maintains a DHCP snooping binding database.

DHCP snooping is a security feature that filters untrusted DHCP messages and builds a DHCP snooping binding database to track valid IP-to-MAC address assignments. It prevents DHCP starvation attacks by rate-limiting DHCP messages on untrusted ports, and it validates DHCP client MAC addresses against the source MAC in the Ethernet frame to prevent MAC spoofing. These three functions directly correspond to the correct answer options.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between trusted and untrusted ports, leading candidates to incorrectly assume that DHCP snooping filters messages on trusted ports or allows server messages from untrusted ports under certain conditions.

Detailed technical explanation

How to think about this question

The DHCP snooping binding database is stored in the switch's memory and maps client MAC addresses, IP addresses, VLANs, and port information, typically with a lease time. Rate-limiting uses the 'ip dhcp snooping limit rate' command to set a maximum number of DHCP packets per second on untrusted ports, mitigating starvation attacks. MAC address validation checks the DHCP client hardware address field against the Ethernet source MAC, dropping packets that do not match, which prevents clients from spoofing a different MAC in DHCP requests.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A practitioner preparing for the 200-301 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

What to study next

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FAQ

Questions learners often ask

What does this 200-301 question test?

Network Services and Security — This question tests Network Services and Security — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: It builds and maintains a DHCP snooping binding database. — DHCP snooping is a security feature that filters untrusted DHCP messages and builds a DHCP snooping binding database to track valid IP-to-MAC address assignments. It prevents DHCP starvation attacks by rate-limiting DHCP messages on untrusted ports, and it validates DHCP client MAC addresses against the source MAC in the Ethernet frame to prevent MAC spoofing. These three functions directly correspond to the correct answer options.

What should I do if I get this 200-301 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

2 more ways this is tested on 200-301

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 three of the following are characteristics of DHCP snooping on a Cisco switch? (Choose three.)

medium
  • .It differentiates trusted and untrusted ports to filter DHCP messages.
  • .It builds and maintains a DHCP snooping binding database.
  • .It prevents DHCP starvation attacks by rate-limiting DHCP messages on untrusted ports.
  • .It encrypts DHCP traffic between the client and the server.
  • .It replaces the DHCP server's IP address with a static route.
  • .It requires all DHCP servers to be connected to untrusted ports.

Why : DHCP snooping is a security feature that filters untrusted DHCP messages by differentiating trusted and untrusted ports. It builds and maintains a DHCP snooping binding database to track valid IP-to-MAC address assignments. Additionally, it prevents DHCP starvation attacks by rate-limiting DHCP messages on untrusted ports, typically using the 'ip dhcp snooping limit rate' command.

Variation 2. Which TWO DHCP snooping trust states are valid on a Cisco switch? (Choose two.)

medium
  • A.Trusted
  • B.Untrusted
  • C.Secure
  • D.Authorized
  • E.Relay

Why A: DHCP snooping is a security feature that filters untrusted DHCP messages on a switch. The only two valid trust states are 'trusted' and 'untrusted'. A trusted port is typically an uplink to a legitimate DHCP server, while an untrusted port is a downstream port where DHCP client messages are expected and server-originated messages are blocked.

Last reviewed: Jun 11, 2026

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