LPIC-2 Advanced Networking Configuration Practice Question
Exhibit
Refer to the exhibit.
# brctl show
bridge name bridge id STP enabled interfaces
br0 8000.001122334455 yes eth0
eth1
# brctl showstp br0
br0
bridge id 8000.001122334455
designated root 8000.001122334455
root port 0 path cost 0
max age 20.00
hello time 2.00
forward delay 15.00
bridge hello time 2.00
bridge max age 20.00
bridge forward delay 15.00
ageing time 300.00
hello timer 0.00
tcn timer 0.00
topology change timer 0.00
gc timer 0.00
eth0 (1)
port id 8001 state forwarding
designated root 8000.001122334455 path cost 4
designated bridge 8000.001122334455 message age timer 0.00
designated port 8001 forward delay timer 0.00
designated cost 0 hold timer 0.00
eth1 (2)
port id 8002 state blocking
designated root 8000.001122334455 path cost 4
designated bridge 8000.001122334455 message age timer 0.00
designated port 8002 forward delay timer 0.00
designated cost 0 hold timer 0.00Hosts connected to eth1 cannot communicate with hosts on eth0. Based on the exhibit, what is the most likely reason?
⚠ Common exam trap
It's easy for candidates to assume a missing IP address on the bridge interface prevents inter-VLAN or inter-host communication, but STP blocking is the actual Layer 2 issue that stops traffic between bridge ports.
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
✓
Spanning Tree Protocol has placed eth1 in blocking state.
The exhibit shows a Linux bridge (br0) with eth0 and eth1 as bridge ports. If hosts on eth1 cannot communicate with hosts on eth0, the most likely cause is that Spanning Tree Protocol (STP) has placed eth1 in a blocking state to prevent a Layer 2 loop. STP blocks redundant paths by transitioning ports through listening, learning, and blocking states, and a blocked port does not forward traffic until the topology converges.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Physical layer issues on eth1.
Why it's wrong here
No indicator of physical issues; the link is up (state is blocking, not down).
- ✗
Eth1 is not connected to the bridge.
Why it's wrong here
Eth1 is listed as an interface of br0.
- ✓
Spanning Tree Protocol has placed eth1 in blocking state.
Why this is correct
The state 'blocking' for eth1 means STP is preventing forwarding to avoid loops.
- ✗
The bridge interface has no IP address.
Why it's wrong here
Bridges operate at L2 and do not require an IP for forwarding.
Visual reference
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-2 practice question is part of Courseiva's free LPI 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 LPIC-2 exam.