VCP-DCV Configure and Manage vSphere Networking Practice Question
An administrator has created a standard vSwitch port group with VLAN ID 100. Virtual machines in this port group can communicate with each other but not with devices on the physical network. What is a possible cause?
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
✓
The physical switch port is not configured to pass VLAN 100.
The issue is that VMs on VLAN 100 can communicate among themselves but not with the physical network. This indicates that VLAN tagging is working within the vSwitch (inter-VM communication works), but the physical switch port is not configured to pass VLAN 100 traffic. The uplink from the ESXi host to the physical switch must be set as a trunk port allowing VLAN 100, or if using an access port, it must be set to VLAN 100. Option A (only one uplink) is sufficient for connectivity. Option B (duplicate MAC addresses) would cause issues even locally. Option D (different subnets) would also affect local communication, but local communication works, so these are not the cause.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The vSwitch has only one uplink.
Why it's wrong here
One uplink is sufficient for connectivity.
- ✗
The virtual machines have duplicate MAC addresses.
Why it's wrong here
Duplicate MACs would cause local issues as well.
- ✓
The physical switch port is not configured to pass VLAN 100.
Why this is correct
The physical switch must allow VLAN 100 on the port.
- ✗
The virtual machines are using different subnets.
Why it's wrong here
Different subnets would prevent local communication.
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 |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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