JNCIE Layer 2 Infrastructure Troubleshooting

1. Which command is used to verify spanning tree topology and port states on a Juniper switch?

Show spanning-tree bridge

Show spanning-tree interface

Show stp topology

Show bridge spanning-tree

Submit

3. What does the 'show ethernet-switching vlan' command display on a Juniper EX switch?

VLAN configuration, members, and interface assignments

Only VLAN IDs

Only trunk port information

Only spanning tree topology

4. Which condition causes a spanning tree port to transition to the 'forwarding' state?

The port completes listening and learning phases without receiving superior BPDUs

The port is assigned to a VLAN

The interface is enabled

The switch is rebooted

Submit

6. The BPDU Guard feature prevents which type of attack or misconfiguration?

Rogue bridge insertion on access ports

MAC address spoofing

VLAN hopping

Port mirroring misuse

7. When troubleshooting a port that is in 'down' state, which is the first diagnostic step?

Check cable connection and optical module health

Immediately disable and re-enable the port

Change the interface MTU

Modify spanning tree priority

8. What does the 'show interfaces' command display regarding interface state on a Juniper switch?

Physical status, MTU, and protocol state

Only MAC address information

Only VLAN assignments

Only spanning tree role

Submit

10. A loop is detected in the network causing broadcast storms. What spanning tree feature prevents this?

Root bridge selection and blocked ports

BPDU guard

Port fast

Root guard

11. Which command displays the MAC address table on a Juniper EX switch?

Show ethernet-switching table

Show mac-address-table

Show bridge table

Show switching database

Submit

13. What is the maximum number of VLANs supported on most Juniper EX series switches?

256

1024

4094

65535

14. In BPDU (Bridge Protocol Data Unit) processing, which field determines the priority of a bridge?

Bridge Priority + System ID Extension

Message Age

Port Cost

Flags field

15. A host connected to an EX switch cannot reach other VLANs. The port is configured as access VLAN 100. What is the most likely issue?

The default gateway or inter-VLAN routing is not configured

VLAN 100 does not exist

The interface is disabled

STP has blocked the port

16. When configuring a trunk port on a Juniper EX switch, which statement is correct?

Set the port mode to 'trunk' and list allowed VLANs

Assign a single VLAN ID to the port

Configure the port as an access port with multiple VLANs

Enable port-based authentication

17. What does the 'show interfaces diagnostics optics' command reveal on a Juniper switch?

Optical module temperature, laser power, and signal integrity

VLAN configuration on the interface

MAC address learning rate

Spanning tree port cost

18. Which spanning tree role does a port assume when it receives superior BPDUs but is not the root port?

Root port

Designated port

Alternate port

Disabled port

19. In Juniper switches, a VLAN is not appearing in the output of 'show vlans'. What is the most likely cause?

The VLAN is configured but not assigned to any interface

The VLAN ID exceeds 4094

The switch does not support VLAN trunking

All interfaces are in access mode

20. What is the primary function of RSTP (Rapid Spanning Tree Protocol) compared to standard STP?

Faster convergence time and BPDU processing

Increased bandwidth utilization

Reduced CPU overhead only

Enhanced security features

JNCIE Layer 2 Infrastructure Troubleshooting Quiz

1. Which command is used to verify spanning tree topology and port states on a Juniper switch?

2.

What first name or nickname would you like us to use?

2. If an interface shows 'carrier transitions' in diagnostic output, this suggests ______.

3. What does the 'show ethernet-switching vlan' command display on a Juniper EX switch?

4. Which condition causes a spanning tree port to transition to the 'forwarding' state?

5. In a Juniper switch, the 'port cost' in spanning tree is determined by ______.

6. The BPDU Guard feature prevents which type of attack or misconfiguration?

7. When troubleshooting a port that is in 'down' state, which is the first diagnostic step?

8. What does the 'show interfaces' command display regarding interface state on a Juniper switch?

9. In Juniper switches, the 'native VLAN' on a trunk port is the VLAN that receives untagged ______.

10. A loop is detected in the network causing broadcast storms. What spanning tree feature prevents this?

11. Which command displays the MAC address table on a Juniper EX switch?

12. When a MAC address floods to all ports, this typically indicates a ______ failure.

13. What is the maximum number of VLANs supported on most Juniper EX series switches?

14. In BPDU (Bridge Protocol Data Unit) processing, which field determines the priority of a bridge?

15. A host connected to an EX switch cannot reach other VLANs. The port is configured as access VLAN 100. What is the most likely issue?

16. When configuring a trunk port on a Juniper EX switch, which statement is correct?

17. What does the 'show interfaces diagnostics optics' command reveal on a Juniper switch?

18. Which spanning tree role does a port assume when it receives superior BPDUs but is not the root port?

19. In Juniper switches, a VLAN is not appearing in the output of 'show vlans'. What is the most likely cause?

20. What is the primary function of RSTP (Rapid Spanning Tree Protocol) compared to standard STP?