Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
Exhibit: A switch port connected to an end host is stuck in a blocking state much longer than expected after a reboot. Which configuration change most directly speeds host access while still keeping loop protection elsewhere?
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
Enable PortFast on the access port
PortFast is the standard fix for host-facing access ports.
B
Distractor review
Disable STP globally
That removes loop protection and is not acceptable.
C
Distractor review
Change the trunk native VLAN
That does not address the STP convergence delay for a host port.
D
Distractor review
Set the port to half-duplex
Duplex has nothing to do with the STP state delay.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A frequent exam trap is selecting the option to disable STP globally to speed up port activation. While this removes the blocking delay, it also eliminates loop protection, risking broadcast storms and network outages. Another trap is thinking that changing the trunk native VLAN or setting the port to half-duplex will speed up host access; these configurations do not affect STP port states or convergence times. Candidates must recognize that only enabling PortFast on access ports safely reduces STP delays without compromising network stability.
Technical deep dive
How to think about this question
Spanning Tree Protocol (STP) is a Layer 2 protocol designed to prevent switching loops by placing redundant paths into a blocking state. When a switch port comes up, STP forces it through listening and learning states before forwarding frames, which typically takes about 30 to 50 seconds. This delay ensures the network topology is stable and prevents temporary loops that could cause broadcast storms. However, this delay is unnecessary for ports connected directly to end devices, which do not create loops. PortFast is a Cisco enhancement that allows access ports connected to end hosts to bypass the STP listening and learning states and transition immediately to the forwarding state. This reduces the time a host waits to gain network access after a reboot or link change from about 30 seconds to just a few seconds. PortFast should only be enabled on ports connected to end devices because enabling it on switch-to-switch links can cause bridging loops and network instability. A common exam trap is to disable STP globally to eliminate the blocking delay, which removes essential loop protection and risks network outages. Another trap is to confuse trunk native VLAN changes or duplex settings with STP behavior; these do not affect STP convergence times. Understanding when and where to apply PortFast is critical for maintaining network stability while optimizing host connectivity times.
KKey Concepts to Remember
- Spanning Tree Protocol (STP) prevents Layer 2 switching loops by placing ports in blocking or forwarding states based on network topology changes.
- PortFast enables an access port connected to an end host to bypass the usual STP listening and learning states and transition immediately to forwarding.
- STP convergence delays on access ports without PortFast cause longer blocking states, delaying host connectivity after a reboot or link change.
- Disabling STP globally removes loop protection across the entire network, which is unsafe and not recommended in production environments.
- Changing the trunk native VLAN does not affect STP port states or convergence times on access ports connected to end devices.
- Setting a port to half-duplex affects collision handling but does not influence STP port state transitions or blocking durations.
- PortFast should only be enabled on ports connected to end hosts, not on ports connecting switches, to avoid creating bridging loops.
- Proper use of PortFast speeds up host access by allowing immediate forwarding while maintaining STP loop protection elsewhere in the network.
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.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
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?
Spanning Tree Protocol (STP) prevents Layer 2 switching loops by placing ports in blocking or forwarding states based on network topology changes.
What is the correct answer to this question?
The correct answer is: Enable PortFast on the access port — PortFast should be enabled on access ports that connect to end devices. It lets the port move to forwarding quickly without waiting through normal STP listening and learning delays.
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.
Discussion
Loading comments…
Sign in to join the discussion.