Is LLDP Configured in Global Configuration Mode?

200-301 By islever Editorial Last updated

Configure and verify Layer 2 discovery protocols (Cisco Discovery Protocol and LLDP)

Short answer

B LLDP is turned on with the global lldp run command, making global configuration mode the correct statement; its timer is adjustable and it is an IEEE Layer 2 protocol.

Question

Which statement about LLDP is true?
  1. It is a Cisco proprietary protocol.
  2. It is configured in global configuration mode. Correct Answer
  3. The LLDP update frequency is a fixed value.
  4. It runs over the transport layer.

Key Takeaways

The item tests where LLDP is enabled versus where it is tuned, and the main trap is treating the 30-second default advertisement interval as an unchangeable fixed value.

LLDP (IEEE 802.1AB) is a vendor-neutral Layer 2 discovery protocol enabled on Cisco devices with the global lldp run command. This page explains why option B is correct and why the proprietary, fixed-timer, and transport-layer claims fail.

Common mistake: Option C is the usual wrong pick: candidates remember the 30-second default and label it fixed, but lldp timer changes the interval while lldp holdtime changes the TTL multiplier.

Expert Analysis

Why B survives scrutiny

LLDP is IEEE 802.1AB, so A is false: Cisco's proprietary neighbor discovery protocol is CDP, while LLDP is the vendor-neutral equivalent. B is the only statement that holds up: on Cisco IOS, LLDP is disabled by default and is turned on with the global command lldp run. That command is the gate that enables advertisements on every interface, so describing LLDP as configured in global configuration mode is accurate even though per-interface tuning exists with lldp transmit, lldp receive, and lldp tlv-select. The statement does not claim global mode is the only place LLDP settings live.

The timer trap in C

C is tempting because the default is 30 seconds and the default holdtime multiplier of 4 yields a 120-second TTL. Neither value is fixed. The global lldp timer <seconds> command changes the advertisement interval, and lldp holdtime <multiplier> changes how long neighbors retain the information. A learner comment that the update timer can be modified captures the issue exactly; calling the frequency fixed confuses the default with an immutable constant.

D and the Layer 2 boundary

D fails because LLDP is an Ethernet data-link protocol using EtherType 0x88CC, not a TCP or UDP payload. That matters operationally: LLDP is not routable, so it discovers only directly connected neighbors, and it must be permitted across the Layer 2 path — access ports, trunks, and AP/WLC infrastructure — for topology discovery to work.

The adjacent decision and what would flip it

The neighboring exam decision is CDP versus LLDP. CDP is Cisco proprietary and normally enabled by default; LLDP is standards-based and disabled by default. If the stem asked which protocol is on by default, the answer would be CDP; if it asked which protocol is vendor-neutral, LLDP. An option claiming LLDP runs over UDP, or that it is enabled out of the box, would be false for the same reasons. If the question asked where to change transmit or receive per port, interface configuration mode would be correct — a change in scope, not protocol.

Operational consequence

Skipping lldp run, or blocking LLDP on a trunk, blinds you to non-Cisco neighbors, breaking topology discovery and voice/PoE troubleshooting. Leaving it on untrusted edge ports leaks platform details, so disable transmit/receive where discovery is not needed. Verify with show lldp, show lldp neighbors, and show lldp interface.

Exam Strategy

When an option describes where a feature is configured, separate enabling from tuning. Ask which command turns the feature on and which commands adjust it per interface. For LLDP, global lldp run is the enabling step; transmit/receive and TLV selection are interface-level. Also translate absolute words like 'fixed' into a test: if a global command such as lldp timer exists, the value is not fixed. Finally, anchor proprietary versus standards-based: CDP is Cisco-only, LLDP is IEEE 802.1AB.

Frequently Asked Questions

Is LLDP enabled by default on Cisco devices?

No. Cisco IOS devices require the global lldp run command because LLDP is disabled by default, unlike CDP, which is normally enabled automatically.

Can the LLDP update frequency be changed?

Yes. The default advertisement interval is 30 seconds, but the global lldp timer command changes it, and lldp holdtime changes the multiplier that determines neighbor hold time.

Why is option C wrong if LLDP sends updates every 30 seconds?

30 seconds is only the default. Because lldp timer can be set to another value, the frequency is configurable rather than fixed.

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Discussion 14 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 14

  1. ian77ex 👍 17
    B is not correct because some LLDP parameters are configured at interface levels (transmit and receive) So it's not only configured at global configuration mode. Maybe the lack of the word "only" makes the answer correct. C is not correct because the update timer can be modified, but anyone could understand the word "fixed" like stating that the updates are sent steadily every a certain amount of 'fixed' time. I hate when they are not trying to measure your knowledge. Instead they're trying to trick you by using unclear questions!
  2. DonnerKomet 👍 10
    No because, C afirms that the frecuency value is a fixed value, but is not true. It can be modified
  3. dearc 👍 5 Answered B
    The answer to the question "Which statement about LLDP is true?" is: B. It is configured in global configuration mode. This answer is supported by search results [1], [2], [3], [4], [5], [6], [7], [8], and [9], which all state that LLDP is configured in global configuration mode . The other statements listed as choices are incorrect. LLDP is not a Cisco proprietary protocol (A) - it is a vendor-neutral protocol. The LLDP update frequency is not necessarily fixed (C) - it can be configured. LLDP runs over the data link layer, not the transport layer (D)
  4. xtraMiles 👍 3 Answered B
    Before you can even use it and do whatever you want to do with it, you first have to enable it in the global config mode because it is disabled by default on Cisco devices. R1(config)#lldp run
  5. ZUMY 👍 3
    B is correct
Show 9 more comments
  1. Stallion 👍 2
    The correct answer to the question is C. The LLDP update frequency is a fixed value. LLDP frames are sent periodically and contain information about the local device. The LLDP update frequency is a fixed value, which means that the amount of time between updates is consistent and determined by the device configuration. By default, the update frequency is 30 seconds. Answer B is incorrect because LLDP is configured on a per-interface basis, not in global configuration mode.
  2. xtraMiles 👍 2
    It can be changed in the configuration. Although, the default is 30 seconds. R1(config)#lldp timer [seconds]
  3. Jbcrggddfhh 👍 2
    B is correct, but C should have been phrased "The LLDP update frequency value can't be modified."
  4. kyleptt 👍 2
    Dumb question because it is out on globally but can be configured per interface.
  5. Liuka_92 👍 2
    I totally agree.
  6. VanessaR05 👍 1 Answered C
    chat GPR Says " C. The LLDP update frequency is a fixed value. Explanation: LLDP is not a Cisco proprietary protocol; it is an industry-standard protocol used for network discovery and information sharing between neighboring devices. The configuration of LLDP is typically done on the interface level, not in global configuration mode. The LLDP update frequency is a fixed value, and it is predetermined by the device configuration. The default update interval is commonly 30 seconds. Therefore, option C is the correct statement about LLDP."
  7. Besxp 👍 1
    Correct answer: B. It is configured in global configuration mode. ✅ Explanation LLDP (Link Layer Discovery Protocol) is a vendor-neutral protocol (IEEE 802.1AB) that allows network devices to advertise information about themselves to directly connected neighbors. On Cisco devices, you enable LLDP globally using global configuration mode: Switch(config)# lldp run
  8. JammyPashmal00 👍 1
    Actually, two answers are correct: LLDP has a fixed timer/frequency (30 sec. by default), and it is configured at the Global command level
  9. squagmire 👍 1
    its just saying that lldp CAN be configured in global mode. its not saying that it cant be configured in interface mode as well

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