ICND1 VLAN Management 3 — Questions and Answers
Question 1: A network administrator wants to prevent a rogue switch from becoming a VTP server. Which action should be taken?
- Set all switches to VTP transparent mode (Correct answer)
- Set all switches to VTP client mode
- Disable VTP pruning
- Configure a VTP domain name of NONE
Correct answer: Set all switches to VTP transparent mode
VTP transparent mode switches do not participate in VTP synchronization, so a rogue switch in transparent mode cannot update the VLAN database.
Question 2: Which command assigns ports Fa0/1 through Fa0/5 to VLAN 30 in a single step on a Cisco switch?
- interface range FastEthernet 0/1-5 then switchport access vlan 30 (Correct answer)
- vlan 30 range fa0/1-5
- switchport vlan 30 range fa0/1 fa0/5
- interface fa0/1-5 switchport mode vlan 30
Correct answer: interface range FastEthernet 0/1-5 then switchport access vlan 30
The 'interface range' command selects multiple interfaces simultaneously, and 'switchport access vlan 30' assigns them all to VLAN 30.
Question 3: What does the 802.1Q tag inserted into an Ethernet frame contain?
- Source MAC, VLAN ID, and CoS bits
- VLAN ID and a 3-bit priority field (CoS) (Correct answer)
- Destination IP and VLAN ID only
- VLAN ID, subnet mask, and frame checksum
Correct answer: VLAN ID and a 3-bit priority field (CoS)
The 4-byte 802.1Q tag includes a 12-bit VLAN ID (supporting VLANs 1–4094) and a 3-bit Class of Service (CoS) priority field.
Question 4: An administrator issues 'switchport trunk allowed vlan 10,20,30' on a trunk interface. What is the effect?
- VLANs 10, 20, and 30 are added to the existing allowed list
- Only VLANs 10, 20, and 30 are allowed; all others are pruned (Correct answer)
- The native VLAN is changed to VLAN 10
- VLANs 10, 20, and 30 are removed from the trunk
Correct answer: Only VLANs 10, 20, and 30 are allowed; all others are pruned
Using 'switchport trunk allowed vlan' (without 'add') replaces the entire allowed list with only the specified VLANs.
Question 5: Which VTP mode allows a switch to create and modify VLANs locally but does not propagate changes to other switches?
- Server mode
- Client mode
- Transparent mode (Correct answer)
- Off mode
Correct answer: Transparent mode
VTP transparent mode lets a switch manage its own local VLAN database without advertising changes to or accepting updates from other VTP devices.
Question 6: What is VLAN pruning in the context of VTP?
- Removing unused VLANs from the VLAN database
- Blocking flooded traffic for VLANs not needed on a trunk (Correct answer)
- Deleting VLANs that have no active ports
- Limiting which VLANs can be created by VTP clients
Correct answer: Blocking flooded traffic for VLANs not needed on a trunk
VTP pruning restricts broadcast, multicast, and unknown unicast traffic from traversing trunk links to switches that have no ports in that VLAN.
Question 7: Which command would you use to configure VLAN 50 with the name 'SERVERS' on a Cisco switch?
- vlan 50 name SERVERS (in global config)
- switchport vlan 50 name SERVERS
- vlan database; vlan 50 name SERVERS (older IOS)
- Both A and C are valid methods depending on IOS version (Correct answer)
Correct answer: Both A and C are valid methods depending on IOS version
Modern IOS uses 'vlan 50' followed by 'name SERVERS' in global config mode; older IOS uses the 'vlan database' mode — both are valid.
ICND1 VLAN Management 3
A network administrator wants to prevent a rogue switch from becoming a VTP server.
Which action should be taken?