JNCIS-ENT Practice Test 8 — 10 Questions

Question 1

Which THREE factors must be considered when configuring a Link Aggregation Group (LAG) with LACP on Junos switches? (Choose three)

Accepted Answer

A minimum number of active links can be configured to ensure traffic drops if bandwidth falls below a threshold.. LAG configuration requires matching speed/duplex, proper device-count definition under chassis, and matching LACP modes.

Answer

VRRP must be enabled on every member port for LACP to negotiate successfully.

Answer

GRES must be enabled on all switches participating in a LAG.

Question 2

Which CLI command is used to manually initiate a Routing Engine switchover on an MX series router configured with GRES?

Accepted Answer

request chassis routing-engine master switch. The 'request chassis routing-engine master switch' command forces a manual switchover from the primary to the backup Routing Engine.

Answer

restart routing-engine backup

Answer

request system reboot backup

Answer

set chassis routing-engine switchover

Question 3

You are troubleshooting a split-brain condition in an EX4300 Virtual Chassis where both partitions have elected a primary Routing Engine. Which feature can be configured to detect this condition and shut down downstream ports on the non-designated partition to prevent duplicate packet forwarding?

Accepted Answer

Virtual Chassis split-detection or auxiliary management connection mechanisms that evaluate reachability between partitions to disable the non-primary partition.. Dual-Routing Engine Advanced Support (DREAS) or specifically configured mechanisms like MAC-sec / split-detection scripts help, but let's look at Juniper's specific Virtual Chassis split-brain mitigation: Junos supports mechanisms such as MAC pinning or specifically configured split detection algorithms, or let's examine standard Juniper terminology. Wait, Junos Virtual Chassis uses Virtual Chassis Automatic Partition Detection or dedicated split-brain detection features. Let's see which option accurately names a valid approach.

Answer

Setting LACP mode to active on the stacking ports.

Answer

Enabling GRES on both partitions simultaneously.

Answer

Configuring VRRP with a priority of 255 on all member interfaces.

Question 4

Which TWO commands are used to verify link aggregation and LACP operational status on a Juniper switch? (Choose two)

Accepted Answer

show interfaces ae0. To verify LACP and LAG status, administrators use 'show lacp interface' and 'show interfaces ae0'.

Answer

show virtual-chassis

Answer

show vrrp detail

Answer

show chassis routing-engine

Question 5

Which THREE actions occur when a Junos router with GRES and NSR enabled performs a manual Routing Engine switchover while running OSPF and BGP? (Choose three)

Accepted Answer

OSPF and BGP daemon states synchronized via NSR allow routing sessions to remain established without neighbor drop.. Control plane state is preserved by NSR, forwarding continues uninterrupted via GRES, and external/internal neighbors do not detect adjacency drops.

Answer

All physical interfaces are reset and re-initialized, causing a 30-second traffic blackout.

Answer

All VRRP virtual gateway IPs revert to their physical interface fallback addresses.

Question 6

When configuring a Link Aggregation Group (LAG) on a Juniper switch, what is the naming convention used for the aggregated interface in the Junos CLI?

Accepted Answer

ae0, ae1, ae2, etc.. Junos uses the 'aeX' naming convention (Aggregated Ethernet) for LAG interfaces.

Answer

lag0, lag1, lag2, etc.

Answer

eth-trunk0, eth-trunk1, etc.

Answer

bond0, bond1, bond2, etc.

Question 7

Which CLI command displays detailed information about VRRP groups, including master router status, virtual IP addresses, and advertisement intervals on an EX series switch?

Accepted Answer

show vrrp detail. The 'show vrrp interface' or 'show vrrp detail' commands provide granular details regarding VRRP instance status.

Answer

show lacp vrrp-status

Answer

show spanning-tree vrrp

Answer

show chassis vrrp

Question 8

An engineer wants to configure a Link Aggregation Group (LAG) to load-balance traffic based on Layer 3 and Layer 4 header fields (source/destination IP and source/destination port) rather than just Layer 2 MAC addresses. How is this achieved in Junos?

Accepted Answer

Configure load-balance profiles under [edit forwarding-options hash-key] specifying inet protocols.. Junos allows configuring load-balancing profiles under the forwarding-options hierarchical level to include IP and port hash fields.

Answer

Enable LACP multi-chassis hashing under the chassis hierarchy.

Answer

Configure 'set interfaces ae0 load-balance layer-3-4' directly under the interface stanza.

Answer

Set the LACP periodic transmission interval to fast.

Question 9

An administrator configures a Link Aggregation Group (LAG) using LACP between two EX series switches. The link fails to aggregate, and the log shows 'LACP status: Expired'. What does the 'Expired' state indicate?

Accepted Answer

The local port has stopped receiving LACP packets from the remote peer within the timeout window.. The 'Expired' state in LACP means the local port has stopped receiving LACP packets from the remote peer within the expected timeout period.

Answer

The Virtual Chassis primary routing engine license has expired.

Answer

The Junos software license for aggregated Ethernet has expired.

Answer

The GRES synchronization timer has timed out.

Question 10

You are configuring Multi-Chassis Link Aggregation (MC-LAG) across two Juniper switches acting as separate control plane devices. Which protocol is used between the peer switches to synchronize state and ensure MAC address table consistency across the MC-LAG domain?

Accepted Answer

Inter-Chassis Control Protocol (ICCP). MC-LAG uses Inter-Chassis Control Protocol (ICCP) to coordinate state, consistency, and status between the two peer switches.

Answer

Open Shortest Path First (OSPF)

Answer

Graceful Routing Engine Switchover (GRES)

Answer

Virtual Router Redundancy Protocol (VRRP)