SK0-005 troubleshooting Practice Question
A medium-size enterprise runs a vSphere 7.0 cluster with two hosts (HostA and HostB) for production VMs. Each host has two 10GbE uplinks (vmnic0 and vmnic1) connected to separate physical switches (SW1 and SW2) for redundancy. A single vSphere standard switch (vSwitch0) uses both uplinks with teaming policy set to 'Route based on originating virtual port ID,' 'Network failure detection: Link status only,' and 'Notify switches: Yes.' Lately, several VMs running on HostA experience intermittent network disconnections lasting 20–30 seconds, while VMs on HostB are unaffected. The administrator checks vCenter events and sees repeated messages: 'Lost uplink redundancy on vSwitch0. vmnic0 is down.' followed seconds later by 'Uplink redundancy restored. vmnic0 is up.' The physical switch SW1's log shows the port for vmnic0 transitions through spanning-tree listening and learning states each time this occurs, taking about 15 seconds. The link is a trunk allowing all necessary VLANs, with no errors or security violations. The network team has already swapped the fiber cable and SFP+ transceiver for vmnic0 without improvement. The VMs affected are those whose virtual ports are pinned to vmnic0 by the load-balancing policy; VMs pinned to vmnic1 never experience disconnections. The administrator has also rebooted HostA and updated the NIC firmware, but the flapping continues. What should the administrator do to permanently resolve the intermittent connectivity?
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
✓
Enable spanning-tree PortFast on the SW1 and SW2 ports connected to the hosts so the ports bypass the listening/learning states.
Option C is correct because the symptoms as confirmed by the switch log show that each link flap triggers spanning-tree recalculation, causing the port to cycle through listening and learning states before forwarding resumes. Enabling PortFast on switch ports that are connected to end devices (like ESXi hosts) allows immediate forwarding. Option A is wrong because changing to access mode would break multiple VLANs and still face STP delays. Option B is wrong because disabling notify switches might worsen MAC table inconsistencies. Option D is wrong because changing load balancing does not stop the flapping or STP convergence; the issue is at layer 2.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Disable the 'Notify switches' option on the vSwitch teaming configuration to avoid unnecessary RARP broadcasts.
Why it's wrong here
Notify switches helps update physical switch MAC tables during failover; disabling it could lead to longer outages or black-holing. It is not the source of the STP delays.
- ✗
Reconfigure the physical switch port for vmnic0 to an access port instead of a trunk to simplify spanning-tree operations.
Why it's wrong here
Changing to access mode would break multiple VLANs required for VMs, and would not prevent the spanning-tree convergence delays.
- ✓
Enable spanning-tree PortFast on the SW1 and SW2 ports connected to the hosts so the ports bypass the listening/learning states.
Why this is correct
The physical switch ports are transitioning through STP states when the link flaps, causing a prolonged outage. Enabling PortFast (or edge port) forces the port directly into forwarding state, eliminating the 15-second delay.
- ✗
Change the NIC teaming load balancing policy to 'Route based on IP hash' to distribute traffic across both uplinks more evenly.
Why it's wrong here
While IP hash can improve load distribution, it does not prevent STP convergence delays caused by link flapping and would not fix the root cause of the flapping or the resulting disconnections.
Visual reference
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
Related to this question
Learn chapter
BIOS/UEFI and Firmware Management
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
Key term
SFP
SFP (Small Form-factor Pluggable) is a compact, hot-swappable transceiver that connects a network device to fiber optic or copper cabling for data transmission.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed July 2026 · checked against the official CompTIA exam blueprint
This SK0-005 practice question is part of Courseiva's free CompTIA 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 SK0-005 exam.