Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A switchport is configured as a trunk on one side and access on the other side of the same physical link. What is the most likely result?
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 link roles are mismatched, so VLAN traffic will not be handled as intended across the link.
This is correct because trunk/access disagreement causes a logical mismatch on the connection.
B
Distractor review
The access side automatically becomes a routed port.
This is wrong because a trunk/access mismatch does not convert the port into a routed interface.
C
Distractor review
The switches automatically synchronize their configurations.
This is wrong because switchport mismatch does not trigger automatic configuration synchronization.
D
Distractor review
The mismatch forces OSPF to choose a new router ID.
This is wrong because OSPF router-ID selection is unrelated to a Layer 2 switchport mismatch.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is to confuse the trunk/access mismatch with Layer 3 routing behaviors or automatic configuration synchronization. Some candidates incorrectly believe that a port configured as access will convert to a routed port or that switches will automatically fix the mismatch. Others mistakenly link the issue to OSPF router ID changes, which are unrelated to Layer 2 switchport roles. This misunderstanding can lead to selecting incorrect answers that mention routing or protocol synchronization instead of focusing on VLAN tagging and port role consistency.
Technical deep dive
How to think about this question
In Cisco networking, a switchport can be configured as either an access port or a trunk port. An access port carries traffic for a single VLAN and is typically used to connect end devices like PCs or printers. A trunk port, on the other hand, carries traffic for multiple VLANs simultaneously by tagging frames with VLAN identifiers using protocols like IEEE 802.1Q. This distinction is fundamental for VLAN segmentation and inter-switch communication in enterprise networks. When one side of a physical link is configured as a trunk and the other side as an access port, a mismatch occurs. The trunk side expects to send and receive tagged frames for multiple VLANs, while the access side expects untagged frames belonging to a single VLAN. This mismatch causes the link to fail in properly forwarding VLAN traffic, leading to connectivity issues and VLAN isolation. Cisco switches do not automatically reconcile this mismatch, so network administrators must ensure consistent port roles on both ends. This trunk/access mismatch is a common exam trap because it can be confused with routing or Layer 3 issues. However, it is strictly a Layer 2 problem related to VLAN tagging and port configuration. Practically, this mismatch results in dropped frames or VLAN leakage, and it does not trigger routing protocol behaviors like OSPF router ID changes. Understanding this helps avoid misdiagnosing network problems and ensures proper VLAN traffic flow across switch links.
KKey Concepts to Remember
- A trunk port forwards traffic for multiple VLANs by tagging frames with VLAN identifiers using IEEE 802.1Q encapsulation.
- An access port carries untagged traffic for a single VLAN and connects end devices to the network.
- A trunk/access mismatch causes VLAN traffic to be mishandled because one side expects tagged frames while the other expects untagged frames.
- Cisco switches do not automatically synchronize or correct mismatched trunk and access port configurations on a link.
- A trunk/access mismatch is a Layer 2 issue affecting VLAN traffic flow and does not impact Layer 3 routing protocols like OSPF.
- Proper VLAN traffic forwarding requires consistent switchport roles on both ends of a physical link.
- Trunk/access mismatches commonly cause connectivity problems such as dropped frames or VLAN isolation in switched networks.
- Understanding switchport roles and VLAN tagging is essential for troubleshooting VLAN-related connectivity issues in Cisco networks.
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?
A trunk port forwards traffic for multiple VLANs by tagging frames with VLAN identifiers using IEEE 802.1Q encapsulation.
What is the correct answer to this question?
The correct answer is: The link roles are mismatched, so VLAN traffic will not be handled as intended across the link. — The most likely result is a mismatch that prevents the link from carrying VLAN traffic as intended between the two switches. In plain language, the two ends of the link do not agree on what the link is supposed to be. One side is trying to carry multiple VLANs with trunk behavior, while the other side is treating the link as a single-VLAN access connection. That mismatch commonly leads to traffic problems and inconsistent operation. This is a standard switchport troubleshooting issue. The correct answer is the one focused on the mismatch in port roles rather than on routing or hostname effects.
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.