Question 455 of 2,015
EtherChannelmediumMultiple SelectObjective-mapped

Quick Answer

The correct answer is that LACP automatically detects speed and duplex mismatches and prevents the channel from forming. This is true because LACP, defined by IEEE 802.3ad, uses Link Aggregation Control Protocol Data Units (LACPDUs) to continuously exchange port parameters between peers; if a mismatch in speed or duplex is detected, the protocol will not allow the link to join the EtherChannel, ensuring stability. On the ENCOR 350-401 exam, this concept tests your understanding of how LACP differs from static EtherChannels, which lack such dynamic verification—a common trap is assuming all EtherChannels automatically handle mismatches. Remember that LACP supports up to 16 links (8 active, 8 standby) and uses active/passive modes for negotiation. A useful memory tip: "LACP checks the specs, or the channel rejects."

CCNP EtherChannel Practice Question

This 350-401 practice question tests your understanding of etherchannel. 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 statements about LACP (Link Aggregation Control Protocol) are true? (Choose three.)

Question 1mediummulti select
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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

LACP packets are exchanged using multicast destination MAC address 01-80-c2-00-00-02.

LACP is an IEEE standard (802.3ad) that allows dynamic formation of EtherChannels. It uses LACPDUs to negotiate parameters, supports up to 16 links (8 active, 8 standby), and can detect mismatched parameters like speed or duplex. The 'active' mode initiates negotiation, while 'passive' waits.

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.

  • LACP packets are exchanged using multicast destination MAC address 01-80-c2-00-00-02.

    Why this is correct

    Correct because LACP uses the Slow Protocols multicast address 0180.c200.0002.

    Related concept

    Static NAT maps one inside address to one outside address.

  • LACP can place up to 8 links in the active state and an additional 8 links in hot-standby mode.

    Why this is correct

    Correct per IEEE 802.3ad, which allows up to 16 links total, with 8 active and 8 standby.

    Related concept

    Static NAT maps one inside address to one outside address.

  • When using LACP, both sides must be configured with the same system priority to form a channel.

    Why it's wrong here

    Incorrect because system priority is used to determine which side controls the channel; they do not need to match.

  • LACP automatically detects speed and duplex mismatches and prevents the channel from forming.

    Why this is correct

    Correct because LACP verifies that all member links have compatible parameters (speed, duplex) before aggregating.

    Related concept

    Static NAT maps one inside address to one outside address.

  • LACP operates only in Layer 3 mode and cannot be used for Layer 2 EtherChannels.

    Why it's wrong here

    Incorrect because LACP works for both Layer 2 and Layer 3 EtherChannels.

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.

What to study next

Got this wrong? Here's your next step.

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 350-401 NAT questions on configuration and troubleshooting.

Related practice questions

Related 350-401 practice-question pages

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FAQ

Questions learners often ask

What does this 350-401 question test?

EtherChannel — This question tests EtherChannel — Static NAT maps one inside address to one outside address..

What is the correct answer to this question?

The correct answer is: LACP packets are exchanged using multicast destination MAC address 01-80-c2-00-00-02. — LACP is an IEEE standard (802.3ad) that allows dynamic formation of EtherChannels. It uses LACPDUs to negotiate parameters, supports up to 16 links (8 active, 8 standby), and can detect mismatched parameters like speed or duplex. The 'active' mode initiates negotiation, while 'passive' waits.

What should I do if I get this 350-401 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 350-401 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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Same concept, more angles

1 more ways this is tested on 350-401

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 statements about LACP (Link Aggregation Control Protocol) are true? (Choose three.)

medium
  • A.LACP uses multicast destination address 01-80-c2-00-00-02 for its frames.
  • B.The LACP system priority is used to determine which switch is the controlling switch in the aggregation.
  • C.LACP port priority is used to select which ports become active when the number of ports exceeds the maximum allowed.
  • D.LACP can negotiate EtherChannels with devices that run PAgP.
  • E.The default LACP system priority on Cisco switches is 32768.

Why A: LACP is an IEEE standard (802.3ad) that allows dynamic EtherChannel formation. It uses system priority and port priority to determine which side controls the aggregation. LACP supports up to 16 links per group (8 active, 8 standby). It can operate in active or passive modes.

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Last reviewed: Jun 18, 2026

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This 350-401 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 350-401 exam.