ICND1 VLAN Management 2 — Questions and Answers
Question 1: Which command verifies that VLAN 10 exists in a switch's VLAN database?
- show vlan brief (Correct answer)
- show interfaces vlan 10
- show ip vlan
- show running-config vlan
Correct answer: show vlan brief
The 'show vlan brief' command displays all VLANs in the VLAN database along with their names and assigned ports.
Question 2: What happens to a port's VLAN membership if you delete its assigned VLAN from the VLAN database?
- The port is automatically moved to VLAN 1
- The port becomes inactive and stops forwarding traffic (Correct answer)
- The port retains its configuration but the VLAN is missing
- The port is converted to a trunk port
Correct answer: The port becomes inactive and stops forwarding traffic
If a VLAN is deleted from the database while ports are still assigned to it, those ports go inactive because they belong to a non-existent VLAN.
Question 3: On a Cisco switch, which file stores VLAN configuration by default when VTP is in server or client mode?
- startup-config
- running-config
- vlan.dat (Correct answer)
- nvram.cfg
Correct answer: vlan.dat
VLAN information is stored in the vlan.dat file in flash memory, separate from the startup-config.
Question 4: A switch port is configured as 'switchport mode access' on VLAN 20. Which statement is true?
- The port carries tagged frames for VLAN 20
- The port can belong to multiple VLANs simultaneously
- The port carries untagged frames belonging to VLAN 20 (Correct answer)
- The port negotiates trunking with the connected device
Correct answer: The port carries untagged frames belonging to VLAN 20
Access ports carry untagged Ethernet frames; the switch internally assigns those frames to the configured access VLAN.
Question 5: Which VLAN range is reserved for Cisco internal use and cannot be created or deleted?
- VLAN 1002–1005 (Correct answer)
- VLAN 1006–4094
- VLAN 1–1000
- VLAN 4090–4094
Correct answer: VLAN 1002–1005
VLANs 1002–1005 are reserved by Cisco for legacy Token Ring and FDDI and cannot be modified or deleted.
Question 6: What is the purpose of the 'switchport nonegotiate' command on a trunk port?
- Forces the port into access mode
- Disables DTP so the port does not send DTP frames (Correct answer)
- Enables manual trunk negotiation
- Sets the native VLAN to VLAN 1
Correct answer: Disables DTP so the port does not send DTP frames
'switchport nonegotiate' prevents the port from sending DTP frames, which is a security best practice on trunk links to non-Cisco devices.
Question 7: Which VLAN is used to carry native (untagged) traffic on an 802.1Q trunk by default?
- VLAN 99
- VLAN 0
- VLAN 1 (Correct answer)
- VLAN 1001
Correct answer: VLAN 1
By default, 802.1Q trunks use VLAN 1 as the native VLAN, meaning frames in VLAN 1 are transmitted without a tag.
ICND1 VLAN Management 2
Which command verifies that VLAN 10 exists in a switch's VLAN database?