Cisco ENCOR Lan Switches 5 — Questions and Answers
Question 1: Which Cisco switching feature allows multiple VLANs to share a single Spanning Tree instance to reduce CPU and memory overhead?
- Rapid PVST+
- PVST+
- Multiple Spanning Tree (MST / 802.1s) (Correct answer)
- Common Spanning Tree (CST)
Correct answer: Multiple Spanning Tree (MST / 802.1s)
MST (802.1s) maps multiple VLANs to a smaller number of STP instances, reducing the per-VLAN processing overhead found in Rapid PVST+.
Question 2: A switch port configured as a trunk receives an untagged frame. What VLAN does the switch assign that frame to?
- VLAN 0
- The native VLAN configured on that trunk port (Correct answer)
- VLAN 4094
- The management VLAN
Correct answer: The native VLAN configured on that trunk port
Untagged frames arriving on an 802.1Q trunk port are placed in the native VLAN configured on that interface.
Question 3: Which command enables Root Guard on a switch port to prevent it from becoming the root port?
- spanning-tree guard root (Correct answer)
- spanning-tree portfast
- spanning-tree bpduguard enable
- spanning-tree vlan 1 priority 0
Correct answer: spanning-tree guard root
Root Guard is enabled per-interface with 'spanning-tree guard root' and places the port in a root-inconsistent state if a superior BPDU is received.
Question 4: In a switch stack using Cisco StackWise technology, what happens if the active stack master fails?
- All switches in the stack reset and re-elect from scratch
- The standby switch becomes the new master within seconds with minimal traffic disruption (Correct answer)
- All ports on the stack are err-disabled
- The stack dissolves into individual switches
Correct answer: The standby switch becomes the new master within seconds with minimal traffic disruption
StackWise elects a standby master that maintains a synchronized copy of the configuration and takes over as active master within seconds if the primary fails.
Question 5: Which Dynamic ARP Inspection (DAI) action causes a switch to drop ARP packets where the sender MAC in the ARP payload differs from the source MAC in the Ethernet header?
- ARP ACL filtering
- DAI source-mac validation (Correct answer)
- IP Source Guard binding check
- DHCP snooping rate limiting
Correct answer: DAI source-mac validation
DAI's source-mac validation check compares the ARP sender hardware address with the Ethernet frame source MAC and drops the packet if they do not match.
Question 6: What is the effect of configuring 'vtp mode transparent' on a Cisco switch?
- The switch forwards VTP advertisements but does not apply them to its local VLAN database (Correct answer)
- The switch becomes a VTP server for all downstream switches
- The switch ignores and discards all VTP messages
- The switch synchronizes its VLAN database with the VTP server
Correct answer: The switch forwards VTP advertisements but does not apply them to its local VLAN database
In VTP transparent mode, the switch passes VTP advertisements to other switches but does not update its own VLAN database based on those advertisements.
Question 7: When configuring EtherChannel load balancing on a Cisco switch, which method distributes traffic based on both source and destination IP addresses?
- src-ip
- dst-ip
- src-dst-ip (Correct answer)
- src-dst-mac
Correct answer: src-dst-ip
The 'src-dst-ip' load-balance method XORs the source and destination IP addresses to select the physical link, providing better distribution across all links in the bundle.
Cisco ENCOR Lan Switches 5
Which Cisco switching feature allows multiple VLANs to share a single Spanning Tree instance to reduce CPU and memory overhead?