easyMultiple SelectObjective-mapped
350-401 Root Port Practice Question
Which two statements about STP port roles and states are true? (Choose two.)
⚠ Common exam trap
Candidates often assume that blocking ports can both send and receive BPDUs, but in classic STP, they only receive BPDUs. Blocking ports do not originate BPDUs.
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
✓
A root port is the port on a non-root bridge that provides the best path to the root bridge.
In classic STP (802.1D), the root port is the port on a non-root bridge that has the best path to the root bridge. A designated port is the port on a segment with the best path to the root bridge, and there is exactly one designated port per segment. A blocking port does not forward user data and only receives BPDUs; it does not send BPDUs. Alternate and backup ports are roles defined in RSTP, not classic STP, and they are in the discarding state, not forwarding or learning.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A root port is the port on a non-root bridge that provides the best path to the root bridge.
Why this is correct
Correct. This is the standard definition of a root port.
- ✗
A designated port is the port on a segment that has the lowest path cost to the root bridge, and there can be multiple designated ports on the same segment.
Why it's wrong here
Incorrect. A designated port is the port with the best path cost to the root bridge on a given segment, but there is exactly one designated port per segment, not multiple.
- ✗
In classic STP, a port in the blocking state can still send and receive BPDUs.
Why it's wrong here
Incorrect. In classic STP, a port in the blocking state only receives BPDUs; it does not send them.
- ✗
An alternate port is a port that provides a backup path to the root bridge and is in the forwarding state when the root port is active.
Why it's wrong here
Incorrect. An alternate port is an RSTP role providing a backup path to the root bridge, but it is in the discarding state, not forwarding.
- ✗
A backup port is a port that provides a redundant connection to the same segment and is in the learning state when the designated port is active.
Why it's wrong here
Incorrect. A backup port is an RSTP role providing a redundant connection to the same segment, but it is in the discarding state, not learning.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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