Tuesday Study Session Flashcards
(12 cards)
Q: What does the command show vlan brief display?
- IP address of VLANs
- Ports in each VLAN and VLAN names
- Trunk configuration
- Native VLAN mismatch
Correct Answer: Ports in each VLAN and VLAN names
Explanation: Displays VLAN IDs, names, and associated ports.
Practical Use: Used to verify VLANs and port assignments.
Why Others Are Incorrect:
- IP addresses are not shown.
- Trunk configuration requires a different command.
- Native VLAN mismatches are not shown.
Objective: VLAN verification
Follow-up: What command creates a new VLAN?
Q: Which command shows if a port is in access or trunk mode?
- show vlan brief
- show interfaces status
- show interfaces switchport
- show ip interface brief
Correct Answer: show interfaces switchport
Explanation: Reveals port mode and VLAN settings.
Practical Use: Essential for identifying misconfigured ports.
Why Others Are Incorrect:
- ‘show vlan brief’ shows port-to-VLAN mapping but not mode.
- ‘show interfaces status’ shows link/duplex.
- ‘show ip interface brief’ is for Layer 3.
Objective: Port mode check
Follow-up: What output field shows ‘Administrative Mode’?
Q: A trunk port isn’t passing VLAN 20. What’s the most useful command?
- show vlan brief
- show interfaces trunk
- show spanning-tree vlan 20
- show mac address-table
Correct Answer: show interfaces trunk
Explanation: Displays allowed and active VLANs on trunk links.
Practical Use: Troubleshoot VLAN traffic issues.
Why Others Are Incorrect:
- ‘show vlan brief’ doesn’t show trunk-specific details.
- Spanning-tree shows blocking, not trunk VLANs.
- MAC table shows learned addresses.
Objective: Trunk diagnostics
Follow-up: What command allows VLAN 20 on a trunk?
Q: What does switchport mode access do?
- Forces port to trunk mode
- Disables trunking, sets to a single VLAN
- Enables negotiation
- Allows all VLANs
Correct Answer: Disables trunking, sets to a single VLAN
Explanation: Puts the port into access mode for end devices.
Practical Use: Ensures ports are dedicated to one VLAN.
Why Others Are Incorrect:
- It disables trunking.
- Negotiation refers to dynamic modes.
- All VLANs require trunk mode.
Objective: Port configuration
Follow-up: What command assigns a VLAN to an access port?
Q: What does switchport trunk allowed vlan 10,20 do?
- Blocks VLANs 10 and 20
- Allows only VLANs 10 and 20
- Tags VLANs 10 and 20
- Enables all VLANs
Correct Answer: Allows only VLANs 10 and 20
Explanation: Restricts traffic to only those VLANs.
Practical Use: Control which VLANs are carried on a trunk.
Why Others Are Incorrect:
- It doesn’t block or tag.
- It restricts, not enables all VLANs.
Objective: VLAN restriction on trunks
Follow-up: What command adds a VLAN without removing existing ones?
Q: What does the command show interfaces trunk help diagnose?
- Duplex mismatch
- Native VLAN mismatch
- MAC flooding
- Port speed mismatch
Correct Answer: Native VLAN mismatch
Explanation: Displays native VLANs on both ends for comparison.
Practical Use: Helps identify tagging problems.
Why Others Are Incorrect:
- Duplex and speed are seen in ‘show interfaces status’.
- MAC flooding is not covered.
Objective: Native VLAN checks
Follow-up: What causes untagged traffic loss on trunks?
Q: A trunk port is connected to a PC. The PC has no access. What’s wrong?
- Port is shutdown
- PC requires VLAN tags
- Port should be access
- Spanning Tree is blocking
Correct Answer: Port should be access
Explanation: PCs need access mode, not trunk mode.
Practical Use: Configure access mode for end devices.
Why Others Are Incorrect:
- Port isn’t necessarily shutdown.
- PCs don’t tag VLANs.
- STP usually blocks loops.
Objective: Correct port role
Follow-up: How do you verify port mode?
Q: What does show mac address-table display?
- IP addresses
- MAC addresses learned per port
- Port duplex mode
- VLAN status
Correct Answer: MAC addresses learned per port
Explanation: Shows which MACs are associated with which ports.
Practical Use: Useful for tracking devices.
Why Others Are Incorrect:
- IPs and duplex info are not shown.
- VLAN info is separate.
Objective: MAC layer checks
Follow-up: Why might a MAC entry disappear from the table?
Q: What command disables trunk negotiation (DTP)?
- switchport nonegotiate
- switchport mode access
- no switchport trunk
- trunk disable
Correct Answer: switchport nonegotiate
Explanation: Prevents automatic trunk negotiation.
Practical Use: Secures trunk setup.
Why Others Are Incorrect:
- Other commands don’t target DTP directly.
Objective: Trunk security
Follow-up: Why is static trunking preferred in secure environments?
Q: What does switchport trunk encapsulation dot1q configure?
- Disables trunking
- Enables 802.1Q tagging
- Adds VLANs to a trunk
- Prunes VLANs
Correct Answer: Enables 802.1Q tagging
Explanation: Sets the trunk to use IEEE 802.1Q protocol.
Practical Use: Ensures compatibility between devices.
Why Others Are Incorrect:
- It doesn’t disable trunking or prune VLANs.
Objective: Trunk protocol configuration
Follow-up: Why is 802.1Q preferred over ISL?
Q: What’s the function of switchport mode dynamic desirable?
- Disables trunking
- Forces access mode
- Initiates trunking if possible
- Enables native VLAN tagging
Correct Answer: Initiates trunking if possible
Explanation: Negotiates trunk if the other side supports it.
Practical Use: Simplifies trunk configuration.
Why Others Are Incorrect:
- Doesn’t force modes or handle tagging.
Objective: DTP behavior
Follow-up: What happens if both sides are set to dynamic auto?
Q: Which command shows link speed, duplex, and VLAN ID for each port?
- show vlan brief
- show interfaces status
- show trunk ports
- show mac address-table
Correct Answer: show interfaces status
Explanation: Summarizes link state and config per interface.
Practical Use: Helps diagnose speed/duplex mismatches.
Why Others Are Incorrect:
- Other commands show different data.
Objective: Interface overview
Follow-up: What does ‘notconnect’ indicate?
