ICND1 LAN Switching Technologies 5 — Questions and Answers
Question 1: Which command enables PortFast on an individual switch interface?
- spanning-tree fast-port
- spanning-tree portfast (Correct answer)
- switchport portfast enable
- spanning-tree mode portfast
Correct answer: spanning-tree portfast
The interface-level command 'spanning-tree portfast' enables PortFast, skipping the listening and learning STP states.
Question 2: What is the maximum number of VLANs supported in the standard VLAN range (not extended)?
- 256
- 1005 (Correct answer)
- 2048
- 4094
Correct answer: 1005
Standard VLANs range from 1 to 1005 on Cisco switches, with some reserved for specific uses.
Question 3: A switch port is in err-disabled state. Which command restores it without manually shutting it down and bringing it back up?
- spanning-tree bpduguard recovery
- errdisable recovery cause bpduguard (Correct answer)
- no errdisable
- spanning-tree portfast recovery
Correct answer: errdisable recovery cause bpduguard
'errdisable recovery cause bpduguard' enables automatic recovery for ports shut down by BPDU Guard.
Question 4: On a Cisco switch, which inter-VLAN routing method uses a single physical trunk link to a router with subinterfaces?
- Layer 3 switching
- Router-on-a-stick (Correct answer)
- SVI routing
- Proxy ARP routing
Correct answer: Router-on-a-stick
Router-on-a-stick uses one physical link with 802.1Q subinterfaces on the router, one per VLAN, for inter-VLAN routing.
Question 5: Which spanning tree port state listens for BPDUs but neither learns MAC addresses nor forwards frames?
- Blocking
- Listening (Correct answer)
- Learning
- Disabled
Correct answer: Listening
The Listening state processes BPDUs to determine topology but does not populate the MAC table or forward data.
Question 6: What is the Cisco term for a per-VLAN implementation of Spanning Tree Protocol running on Cisco switches?
- MSTP
- RSTP
- CST
- PVST+ (Correct answer)
Correct answer: PVST+
Per-VLAN Spanning Tree Plus (PVST+) runs a separate STP instance for each VLAN, allowing per-VLAN root bridge selection.
Question 7: Which command verifies the root bridge, port roles, and port states for VLAN 10 on a Cisco switch?
- show vlan id 10
- show spanning-tree vlan 10 (Correct answer)
- show interfaces vlan 10
- show mac address-table vlan 10
Correct answer: show spanning-tree vlan 10
'show spanning-tree vlan 10' displays STP details including the root bridge ID, local bridge ID, and each port's role and state.
ICND1 LAN Switching Technologies 5
Which command enables PortFast on an individual switch interface?