mediumMultiple Choice
CCNP Is true about the STP max age timer? Practice Question
Which of the following is true about the STP max age timer?
⚠ Common exam trap
Cisco often tests the max age timer by confusing it with the forward delay timer or the hello timer, so candidates mistakenly associate it with port state transition durations rather than its actual role in aging out BPDU information.
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 is the maximum time a switch stores BPDU information before discarding it.
The STP max age timer defines the maximum time a switch will store a received BPDU before discarding it. If a switch does not receive a new BPDU from the root bridge within this interval (default 20 seconds), it assumes the root bridge has failed and initiates a topology change, recalculating the spanning tree.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It is the time a port spends in the listening state.
Why it's wrong here
The time a port spends in the listening state is governed by the forward delay timer, not max age. In classic STP, listening and learning each last forward-delay seconds (default 15), while max age defaults to 20 seconds and controls BPDU aging. This option confuses the forward-delay timer with the max-age timer, which are entirely separate STP parameters.
- ✗
It is the interval between BPDU transmissions.
Why it's wrong here
The interval between BPDU transmissions is called the hello time, which defaults to 2 seconds on Cisco switches. The hello timer controls how often the root bridge sends configuration BPDUs, whereas max age is the timer that determines how long a switch will wait before discarding stored BPDU information. Confusing these two timers is a common error, but they serve different purposes and have different default values.
- ✓
It is the maximum time a switch stores BPDU information before discarding it.
Why this is correct
Max age is the STP timer that dictates how long a switch will store BPDU information before considering it stale. By default, this is 20 seconds; if no new BPDU arrives from a neighbor within that window, the switch discards the outdated information and may trigger a topology recalculation. This ensures that no switch acts on obsolete root or path information, which could result in loops or suboptimal forwarding paths.
- ✗
It is the time a port waits before transitioning from blocking to listening.
Why it's wrong here
The transition from blocking to listening is instantaneous after a port is enabled—there is no waiting period or timer that delays this specific state change. Max age applies to the aging of received BPDUs, not to the state machine's transition from blocking to listening. This option incorrectly associates max age with a phase of port state progression, when in reality max age is a data-aging mechanism for BPDUs.
Visual reference
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.