JNCIP-ENT Practice Test 17 — 15 Questions

Question 1

Which statement correctly describes the function of an OSPF Stub Area?

Accepted Answer

Stub areas block external AS-external (Type-5) LSAs and use a default route injected by the ABR.. Stub areas block external Type-5 LSAs and instead rely on a default route injected by the ABR.

Answer

Stub areas allow bidirectional redistribution of BGP routes.

Answer

Stub areas block inter-area summary (Type-3) LSAs.

Answer

Stub areas allow Type-7 LSAs from external ASBRs.

Question 2

An administrator implements MSTP (Multiple Spanning Tree Protocol) in a large data center using Juniper switches. Region boundaries must be maintained strictly. Which three parameters must match identically across all switches for them to be considered part of the same MST region?

Accepted Answer

Region name, revision number, and VLAN-to-instance mapping. MST region configuration requires identical configuration name, revision number, and VLAN-to-instance mapping table.

Answer

MAC address, revision number, and region name

Answer

Bridge priority, hello time, and max age

Answer

Extended system ID, region name, and forward delay

Question 3

Which TWO parameters are part of the standard MSTP configuration digest computed across switches in an MST region? (Choose two)

Accepted Answer

MST configuration name. The MST configuration digest includes region name, revision number, and the VLAN-to-instance allocation table.

Answer

Bridge priority value

Answer

Interface MAC addresses

Answer

Hello time and max age timers

Question 4

When designing a BGP confederation architecture, which TWO rules govern how sub-AS numbers and attributes behave across confederation boundaries? (Choose two)

Accepted Answer

Sub-AS numbers are included in AS_CONFED_SEQUENCE attributes and are stripped when exiting the confederation.. Confederations use AS_CONFED_SEQUENCE and AS_CONFED_SET segments to track internal paths, and strip them when advertising to external peers outside the confederation.

Answer

BGP multipath cannot be enabled across different member ASNs within the same confederation.

Answer

MED values are automatically removed across member AS boundaries regardless of configuration.

Answer

Local preference is discarded when passing routes between different member ASNs inside the confederation.

Question 5

Which TWO actions can be performed using Junos BGP routing policies? (Choose two)

Accepted Answer

Modifying the local preference attribute of incoming IBGP routes.. Option A is correct because Junos routing policies applied as import policies can match incoming IBGP routes and set the BGP local preference attribute (for example with the 'then local-preference' action), which influences outbound path selection within the local AS. Option C is correct because Junos policy-options support AS path regular expressions via the 'as-path' match condition, allowing routes to be filtered or manipulated based on the AS_PATH attribute. Option B is not valid because BGP TCP port 179 is fixed by the protocol and cannot be changed by routing policy; port configuration is not a policy action. Option D is not valid because keepalive and hold timers are configured under the BGP neighbor or group hierarchy, not dynamically modified through policy match/action statements. Option E is not valid because interface MTU is a physical/logical interface property configured under interfaces, not something a BGP routing policy can assign.

Answer

Dynamically altering the BGP session TCP handshake port numbers.

Answer

Adjusting the BGP keepalive timer values dynamically via policy match actions.

Answer

Manually assigning physical interface MTU sizes for BGP sessions.

Question 6

When deploying IP phones that utilize a voice VLAN on EX Series access ports, which THREE characteristics or configurations typically apply to this design? (Choose three.)

Accepted Answer

Untagged traffic generated by an attached PC passes through the phone into the native VLAN of the switch port.. Option B is correct because in a typical voice VLAN deployment the PC's untagged frames are forwarded by the phone and land in the switch port's native (data) VLAN, keeping PC traffic separate from voice traffic. Option C is correct because the access port carries both a native data VLAN for the attached PC and a tagged voice VLAN for the phone, which is the standard EX Series access-port voice VLAN design. Option D is correct because the IP phone itself applies the 802.1Q tag with the configured voice VLAN ID to its own voice frames, which is how the switch distinguishes voice from data. Option A is wrong because a pure Layer 3 routed interface does not carry 802.1Q-tagged voice VLAN traffic in this access-port design. Option E is wrong because BGP is a routing protocol between Layer 3 devices and has no role in phone-to-switch voice VLAN tagging or access-port operation.

Answer

The switch port must be configured as a pure Layer 3 routed interface.

Answer

The IP phone must be configured to run BGP to exchange voice routes with the switch.

Question 7

Which configuration stanza is used to define custom forwarding classes in Junos?

Accepted Answer

[edit class-of-service forwarding-classes]. Custom forwarding classes are defined under the [edit class-of-service forwarding-classes] hierarchy.

Answer

[edit class-of-service drop-profiles]

Answer

[edit class-of-service classifiers]

Answer

[edit class-of-service schedulers]

Question 8

Which TWO statements describe the behavior of VSTP (VLAN Spanning Tree Protocol) on Juniper EX Series switches? (Choose two)

Accepted Answer

VSTP can interoperate with Cisco's PVST+ protocol.. VSTP runs an independent spanning tree instance per VLAN and interoperates with PVST+.

Answer

VSTP is incompatible with RSTP fallback modes.

Answer

VSTP automatically disables all trunk ports if BPDU guard is triggered globally.

Answer

VSTP requires all VLANs to be mapped into a single master MSTI region.

Question 9

When configuring advanced Layer 2 tunneling (Q-in-Q) on Juniper EX Series switches, which THREE statements are correct regarding VLAN stacking behavior and limitations? (Choose three)

Accepted Answer

MTU sizes across the core must be adjusted to account for the extra 4 bytes of the added outer VLAN tag.. QinQ on Juniper EX switches involves specific encapsulation requirements like flexible-ethernet-services, stacking VLAN tags on ingress and popping on egress, and preserving inner customer VLAN tags transparently.

Answer

Layer 2 Protocol Tunneling (L2PT) is automatically enabled for all protocols without additional configuration when QinQ is active.

Answer

QinQ tunneling requires standard access mode encapsulation on all core-facing uplink ports.

Question 10

Which TWO statements are correct regarding captive portal redirection behavior on EX Series switches? (Choose two)

Accepted Answer

Clients can be granted pre-authentication access to specific IP addresses using a walled garden or bypass list.. Option A is correct because EX Series captive portal supports a walled garden (bypass list) that allows unauthenticated clients to reach specific IP addresses or domains—such as DNS, DHCP, or authentication servers—before they log in. Option D is correct because the switch intercepts unauthenticated HTTP requests and redirects them to the captive portal login URL, which is the core mechanism of captive portal redirection. Option B is incorrect because captive portal authentication is browser-based and does not require any proprietary Juniper client agent. Option C is incorrect because HTTPS traffic is not decrypted or redirected; certificate errors would occur if interception were attempted, so HTTPS is typically blocked or bypassed rather than transparently redirected. Option E is incorrect because redirection is performed by the switch intercepting HTTP traffic, not by modifying client OS registry settings via DHCP.

Answer

Captive portal redirection requires the client to run a proprietary Juniper client software agent.

Answer

HTTPS traffic is automatically decrypted and redirected without client browser certificate errors.

Answer

Redirection is achieved by modifying the client's local operating system registry settings via DHCP.

Question 11

When designing advanced enterprise campus VLAN architectures with Juniper EX Series switches, which TWO considerations are critical for large-scale Layer 2 domains? (Choose two)

Accepted Answer

Configuring bridge assurance on all point-to-point links running MSTP to protect against unidirectional link failures.. In large-scale Layer 2 networks, keeping broadcast domains small and controlling failure domains via multi-chassis link aggregation (MC-LAG or EVPN-VXLAN) and limiting spanning tree blast radius are essential design principles.

Answer

Disabling BPDU protection on core inter-switch links to allow unexpected root bridges to take over seamlessly.

Answer

Enabling spanning tree globally across all VLANs without instance mapping to ensure all switches share a single root bridge.

Answer

Setting the forward delay timer to 4 seconds across all switches to accelerate MSTP topology convergence.

Question 12

An enterprise network engineer is designing a redundant Layer 2 topology with MSTP across Juniper EX switches. Two switches have identical bridge priorities and MAC addresses that result in a tie for regional root. How does MSTP deterministically break the tie to select the regional root bridge?

Accepted Answer

The switch with the numerically lowest MAC address is selected as the root bridge.. Spanning tree tie-breaking checks the bridge priority first, and if tied, compares the lowest MAC address of the switches.

Answer

The switch with the highest interface count operational status wins.

Answer

The switch with the higher serial number stored in EEPROM is chosen.

Answer

MSTP triggers a randomized tie-breaker algorithm using the system uptime.

Question 13

An administrator needs to configure PoE power management on an EX3400 switch to prioritize port ge-0/0/0 for a critical emergency IP phone. Which statement correctly describes the default PoE priority behavior on Junos EX switches if no explicit priority is configured?

Accepted Answer

All ports default to low priority, and power allocation is determined by port index order when budgets are constrained.. By default, all PoE ports on Junos EX switches are set to low priority. When the power budget is constrained, power allocation is determined by port index order (e.g., ge-0/0/0 before ge-0/0/1). This means that lower-numbered ports are given precedence. To prioritize a critical port, you must explicitly configure a higher priority.

Answer

All ports default to high priority and allocate power on a first-come, first-served basis.

Answer

PoE is disabled by default until an explicit priority is assigned to the interface.

Answer

Critical ports must be placed in a dedicated PoE policer to prevent disconnection.

Question 14

You are troubleshooting a power budget shortfall on an EX4300 switch where multiple PoE devices are failing to power up. Which TWO actions can you take to resolve or mitigate this power deficit? (Choose two.)

Accepted Answer

Configure critical IP phone ports with a high PoE priority so they are not shut down during a power deficit.. Option C is correct because on EX4300 PoE ports you can assign a PoE priority (for example, high) so that during a power budget deficit the switch sheds lower-priority ports first and preserves power for critical IP phones. Option D is correct because you can manually control per-port power allocation using the 'power-limit' configuration with either class/consumption mode or an explicit wattage value, reducing the total allocated power and bringing the budget back within the switch's capacity. Options A, B, and E do not address PoE power budgeting: disabling LLDP-MED would not reduce power draw and could actually disrupt phone power negotiation, RSTP root guard is a Layer 2 loop-prevention feature unrelated to PoE, and converting access ports to trunks has no effect on power consumption or allocation.

Answer

Disable LLDP-MED globally to force all phones to draw maximum class power.

Answer

Enable RSTP root guard on all voice interfaces.

Answer

Convert all access ports to trunk ports.

Question 15

You are designing an EVPN network with active-active multi-homing. A host sends traffic to a multi-homed PE. The PE receives the traffic on a designated link. How does EVPN suppress unnecessary flooding across the core for unknown unicast traffic originating from a multi-homed site?

Accepted Answer

By dynamically learning MAC addresses via control-plane Type 2 routes, turning unknown unicast into known unicast.. EVPN suppresses unknown unicast flooding by performing MAC learning via control-plane advertisement (Type 2 routes) upon first contact, so subsequent traffic is unicast-forwarded rather than flooded.

Answer

By utilizing Spanning Tree Protocol to block redundant ports across the core.

Answer

By dropping all packets with unknown destination MAC addresses at the ingress leaf.

Answer

By enforcing ingress replication drop filters on Type 3 routes.