JNCIS-ENT Practice Test 8 — 10 Questions

Question 1

When configuring an IP-IP tunnel on a Junos device, what happens to the source and destination IP addresses of the original packet when it is encapsulated?

Accepted Answer

The original packet is placed inside a new outer IP header, leaving the inner IP header and its source/destination unchanged.. IP-IP tunneling (RFC 2003) encapsulates the original IP packet inside a new outer IP header. The inner IP header, including original source and destination addresses, remains unchanged. The outer header uses the tunnel endpoints' addresses.

Answer

The original packet has its source address replaced by the tunnel interface address and destination kept intact.

Answer

The original source and destination IP addresses are overwritten by the tunnel endpoint addresses.

Answer

The original packet header is stripped and replaced entirely by a GRE header.

Question 2

An administrator wants to gracefully restart a BGP routing daemon without dropping the underlying TCP session or causing traffic loss. Which Junos feature should be enabled?

Accepted Answer

BGP Graceful Restart. Graceful Restart allows a BGP speaker to express its ability to preserve forwarding state while restarting the control plane.

Answer

Nonstop Active Routing (NAR)

Answer

TCP MD5 Signature bypass

Answer

BGP Bidirectional Forwarding Detection (BFD)

Question 3

You need to configure authentication for a BGP peering session on a Junos device to prevent spoofing attacks. Where is the MD5 authentication key configured?

Accepted Answer

protocols bgp group name authentication-key. BGP MD5 authentication keys are configured under the specific neighbor or group definition using the authentication-key statement.

Answer

firewall family inet filter bgp-auth

Answer

system authentication-algorithm md5

Answer

routing-options md5-key

Question 4

Which level is enabled by default in Junos when configuring IS-IS on an interface?

Accepted Answer

Level 1 and Level 2. By default, interfaces in Junos IS-IS are enabled for both Level 1 and Level 2.

Answer

None

Answer

Level 2 only

Answer

Level 1 only

Question 5

When configuring VRRP on a Juniper router, what IP address must be assigned as the virtual IP address for the group?

Accepted Answer

An IP address belonging to the same subnet as the physical interface connected to the broadcast domain.. The virtual IP address must belong to the same subnet as the physical interface IP address configured on the participating routers.

Answer

A loopback IP address configured on the master Routing Engine.

Answer

A public IP address provided by your upstream Internet Service Provider.

Answer

A reserved multicast address in the 224.0.0.18 range.

Question 6

What is the function of the DIS in an IS-IS broadcast network?

Accepted Answer

To generate pseudonode LSPs.. The DIS (Designated Intermediate System) is responsible for generating pseudonode LSPs to represent the broadcast network.

Answer

To authenticate all neighbors.

Answer

To perform path calculation for all routers.

Answer

To act as the routing controller for the area.

Question 7

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 8

Which Junos command displays the active DHCP snooping binding database entries on an EX Series switch?

Accepted Answer

show ethernet-switching dhcp-snooping binding. The operational command to view DHCP snooping bindings is 'show ethernet-switching dhcp-snooping binding'.

Answer

show dhcp-snooping binding

Answer

show system dhcp-snooping database

Answer

show bridge dhcp bindings

Question 9

An administrator runs 'show vlans' and notices that a particular VLAN has the status 'Active' but no interfaces listed under it. What does this indicate?

Accepted Answer

The VLAN is defined in the configuration and has an active IRB interface or routing instance, but no physical switch ports assigned.. An active VLAN without interfaces means the VLAN is defined in the database and associated with an IRB (Layer 3 interface) or routing instance, but no physical switch ports are members.

Answer

The VLAN has been disabled by Spanning Tree Protocol.

Answer

The switch memory is full and cannot display interface memberships.

Answer

The VLAN configuration has a syntax error.

Question 10

When a topology change occurs in an RSTP network, how are MAC address forwarding table entries affected across the switches?

Accepted Answer

MAC address table entries associated with non-edge ports are flushed immediately.. When a topology change occurs in RSTP, MAC address table entries associated with non-edge ports are flushed immediately. This allows the switches to relearn MAC addresses on the new topology, preventing forwarding to stale locations. Edge ports are not flushed because they connect to end devices and are not affected by topology changes.

Answer

MAC addresses are relearned only after the root bridge sends a direct clearing command.

Answer

MAC address entries are retained until the standard 300-second aging timer expires.

Answer

MAC address tables are completely cleared for all ports, including edge ports.