LFCS Networking Practice Question
Which nmcli command creates a VLAN interface with tag 10 on device eth0?
⚠ Common exam trap
Many exam-takers confuse `ifname` (which sets the resulting interface name) with `dev` (which specifies the parent device), leading candidates to incorrectly use `ifname eth0` instead of `dev eth0` when the intent is to attach the VLAN to the physical interface.
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
✓
nmcli connection add type vlan con-name vlan10 dev eth0 id 10
The `nmcli connection add` command with `type vlan` requires the `dev` option to specify the parent interface (eth0) and the `id` option to set the VLAN tag (10). The `con-name` assigns a name to the connection profile, and the resulting interface will be named automatically (e.g., eth0.10) unless overridden by `ifname`. This creates a VLAN interface that tags frames with ID 10 on the parent device eth0.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
nmcli connection add type vlan con-name vlan10 ifname eth0 id 10
Why it's wrong here
The correct parameter is 'dev', not 'ifname'.
- ✓
nmcli connection add type vlan con-name vlan10 dev eth0 id 10
Why this is correct
This is the correct syntax to create a VLAN connection on eth0 with ID 10.
- ✗
nmcli device add vlan con-name vlan10 dev eth0 id 10
Why it's wrong here
'nmcli device add' is not a valid command.
- ✗
nmcli connection add type vlan con-name vlan10 ifname eth0.10
Why it's wrong here
This would create a connection with a specific ifname but not necessarily a VLAN.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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