Question 1mediummulti select
Full question →mediummulti selectObjective-mapped
Which two STP facts are correct? Choose two.
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
The root bridge is elected using the lowest bridge ID
That is how the root bridge is selected.
B
Best answer
STP is designed to prevent Layer 2 switching loops
Loop prevention is the whole reason STP exists.
C
Distractor review
A lower path cost makes a port less likely to become root port
Lower cost is exactly what a switch prefers toward the root.
D
Distractor review
All blocked ports are designated ports
Blocked ports are not designated forwarding ports.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is confusing the role of path cost in STP port selection. Some may incorrectly believe that a lower path cost makes a port less likely to become a root port, but in reality, STP prefers the lowest cost path to the root bridge, making that port the root port. Another trap is assuming all blocked ports are designated ports, which is false because blocked ports do not forward traffic and are specifically placed to prevent loops. Misunderstanding these details can lead to selecting incorrect answers about STP port roles and root bridge election.
Technical deep dive
How to think about this question
Spanning Tree Protocol (STP) is a Layer 2 network protocol designed to prevent switching loops in Ethernet networks by selectively blocking redundant paths. STP elects a root bridge, which serves as a reference point for all path calculations. Each switch uses the root bridge ID, a combination of priority and MAC address, to determine the root bridge, with the lowest bridge ID winning the election. This root bridge then influences port roles and forwarding decisions across the network. STP assigns port roles based on path cost to the root bridge. Each non-root switch selects a single root port, which is the port with the lowest cumulative cost path back to the root bridge. Ports on the root bridge itself are always designated ports, forwarding traffic for their segments. Ports that could cause loops are placed into a blocking state and are not designated ports. This mechanism ensures a loop-free topology while maintaining redundancy. A common exam trap is misunderstanding the relationship between port cost and port roles. Lower path cost ports are more likely to become root ports, not less, which contradicts option C. Also, blocked ports are never designated ports, as option D incorrectly states. Understanding these distinctions is critical for correctly answering STP questions and for practical network design, where proper port roles ensure stability and redundancy without loops.
KKey Concepts to Remember
- STP elects the root bridge by selecting the switch with the lowest bridge ID, which combines priority and MAC address.
- STP prevents Layer 2 switching loops by placing some ports into a blocking state to stop redundant traffic paths.
- Each non-root switch selects one root port as its lowest-cost path back to the root bridge to forward traffic.
- Ports on the root bridge are always designated ports, forwarding traffic for their directly connected segments.
- Blocked ports in STP do not forward traffic and are never designated ports, preventing Layer 2 loops.
- STP uses path cost metrics to determine port roles, preferring lower cost paths toward the root bridge.
- The root bridge acts as the central point for all STP calculations and influences port role assignments network-wide.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
STP elects the root bridge by selecting the switch with the lowest bridge ID, which combines priority and MAC address.
What is the correct answer to this question?
The correct answer is: The root bridge is elected using the lowest bridge ID — STP prevents Layer 2 loops by placing some ports into a non-forwarding role. The root bridge is chosen by the lowest bridge ID, and all ports on the root bridge itself are designated ports for their segments.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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