JNCIP-ENT Practice Test 2 — 30 Questions

Question 1

An administrator implements BGP entropy labels and path load balancing on a Junos routing platform. During packet forwarding for a BGP-learned IPv4 prefix with multiple equal-cost paths, how does Junos determine the output interface when hash-based load balancing is active?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Hashing selected packet header fields to compute an index into the set of resolved BGP next hops.. Junos hashes packet header fields (such as source/destination IP, ports, and optional hash keys or entropy labels) to select a specific path from the available BGP multipaths.

Answer

Using the lowest MED value among the multipath entries for every packet transmission.

Answer

Consulting the BGP Route Reflector cluster list to determine the optimal egress port.

Answer

Round-robin packet scheduling across all available BGP next hops regardless of flow headers.

Question 2

Which TWO attributes are considered transitive BGP path attributes? (Choose two)

Accepted Answer

COMMUNITY. AS_PATH and COMMUNITY are standard well-known transitive and optional transitive attributes respectively, whereas LOCAL_PREF is well-known discretionary (non-transitive across AS).

Answer

MED (Multi-Exit Discriminator)

Answer

ORIGINATOR_ID

Answer

LOCAL_PREF

Question 3

An administrator needs to ensure that a Junos routing device performs unequal-cost multi-path (UCMP) load balancing across multiple BGP paths with different local preferences or path attributes. Which BGP feature must be enabled to allow multipath load balancing across paths with different AS path lengths?

Accepted Answer

set protocols bgp multipath as-path-ignore. By default, Junos multipath requires multiple attributes (such as AS path length) to match. To allow BGP multipath even when AS path lengths differ (as long as they have the same length numerically, or using 'as-path-ignore'), the 'as-path-ignore' statement under protocols bgp multipath must be configured.

Answer

set protocols bgp family inet unicast multipath relax

Answer

set routing-options rib inet.0 multipath

Answer

set protocols bgp load-balance per-packet

Question 4

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 5

A Junos router is configured with BGP path selection, and multiple paths arrive with different MED values. Under what specific condition does Junos compare the MED values of paths from different autonomous systems during route selection?

Accepted Answer

Junos compares MEDs from different ASs only when the 'always-compare-med' statement is configured under protocols bgp.. By default, Junos (like standard BGP implementations) only compares MEDs from different ASs if the 'always-compare-med' configuration is explicitly enabled.

Answer

Junos compares MEDs from different ASs when the AS path lengths are completely identical.

Answer

Junos never compares MEDs from different ASs under any circumstance.

Answer

Junos compares MEDs from different ASs automatically if the routes share the same IGP metric.

Question 6

An administrator configures BGP dampening on a Junos router to mitigate the impact of flapping routes. When a route exceeds the reuse threshold after being suppressed, what happens to its penalty value?

Accepted Answer

The penalty value continues to decay exponentially until it drops to zero.. When a dampened route's penalty decays below the reuse threshold, the route becomes eligible again, and its penalty continues to decay exponentially toward zero.

Answer

The penalty value is locked at the reuse threshold value indefinitely.

Answer

The penalty value is doubled to discourage further flapping.

Answer

The penalty value is instantly reset to zero.

Question 7

Which THREE optional BGP attributes are supported and processed by Junos routing devices? (Choose three)

Accepted Answer

COMMUNITY. Junos supports standard optional attributes such as MED, Communities, and Atomic Aggregate.

Answer

LOCAL_WEIGHT

Answer

NEXT_HOP_OVERRIDE

Question 8

A Junos router receives a BGP route containing multiple extended and large communities. The administrator writes a routing policy to filter routes based on large communities. Which format is used to define a large community in Junos policy-options?

Accepted Answer

large-community:global_administrator:local_data1:local_data2. Large communities in Junos policy-options are defined using the format large-community:global_administrator:local_data1:local_data2.

Answer

as-number:identifier

Answer

target:as-number:identifier

Answer

ipv4-address:identifier

Question 9

Which THREE types of classifiers are natively supported in Junos Class of Service? (Choose three)

Accepted Answer

exp. Junos supports multiple classifier types including dscp, exp, and ieee-802.1.

Answer

tcp-port

Answer

mac-address

Question 10

An enterprise is designing a BGP confederation to reduce iBGP mesh complexity across multiple data centers. Which statement is correct regarding how confederation members interact with BGP attributes?

Accepted Answer

Sub-AS numbers are preserved in AS_CONFED_SEQUENCE segments inside the confederation but are replaced by the confederation identifier when advertising to external peers.. Within a BGP confederation, sub-AS numbers are stripped as routes leave the confederation and are replaced by the confederation identifier. However, within the confederation, sub-AS numbers are kept in the AS_CONFED_SEQUENCE and AS_CONFED_SET path segments to prevent loops, and MED/Local Preference are preserved across member sub-AS boundaries.

Answer

Confederations eliminate the need for any internal iBGP peering within the member sub-ASes.

Answer

The next-hop IP address is always modified when routes are passed between member sub-ASes within the confederation.

Answer

Local Preference is automatically reset to zero whenever a route crosses a sub-AS boundary inside a confederation.

Question 11

What is the default number of forwarding classes available on Juniper MX Series routers equipped with Modular Port Concentrators (MPCs)?

Accepted Answer

64. Junos supports up to 64 forwarding classes on modern MPC-based hardware platforms, though default configurations typically use a subset.

Answer

4

Answer

8

Answer

16

Question 12

What is the primary function of a behavior aggregate (BA) classifier in Junos CoS?

Accepted Answer

It classifies packets based exclusively on header CoS bits such as DSCP or EXP. A Behavior Aggregate (BA) classifier classifies packets based solely on the CoS bits in the packet header (such as DSCP, EXP, or IEEE 802.1p).

Answer

It drops packets exceeding a predefined bandwidth rate

Answer

It rewrites VLAN tags on egress interfaces

Answer

It classifies packets based on Layer 4 port numbers and source IP addresses

Question 13

Which command displays the configured scheduler maps and their association with forwarding classes on a Junos device?

Accepted Answer

show class-of-service scheduler-map. The show class-of-service scheduler-map command displays details of scheduler maps and queue associations.

Answer

show class-of-service queue

Answer

show class-of-service forwarding-class

Answer

show configuration class-of-service schedulers

Question 14

Which TWO statements are correct regarding the behavior of policers in Junos? (Choose two)

Accepted Answer

Policers can mark the loss priority of exceeding packets. Policers can drop traffic or mark loss priority, and they operate based on token bucket algorithms.

Answer

Policers buffer exceeding packets in temporal memory queues until transmission capacity opens

Answer

Policers are always applied to egress interfaces only

Answer

Policers guarantee a minimum bandwidth allocation for best-effort traffic

Question 15

Which THREE components are required to fully configure a custom Class of Service scheme on an MX Series router? (Choose three)

Accepted Answer

schedulers. Implementing custom CoS requires forwarding classes, classifiers, and schedulers.

Answer

dynamic-profiles

Answer

bgp-routes

Question 16

You want to configure voice VLAN functionality on a Juniper EX switch so that IP phones automatically place voice traffic into VLAN 50 while passing PC data through unchanged. Which feature should you configure?

Accepted Answer

LLDP-MED with voice VLAN assignment. Voice VLAN feature on EX switches automatically assigns voice traffic from known MAC OUIs to the designated voice VLAN.

Answer

MAC-based RADIUS dynamic VLAN assignment

Answer

Layer 2 protocol tunneling (L2PT)

Answer

IEEE 802.1X supplicant authentication

Question 17

You are configuring Ethernet switching on an EX4300 switch and need to implement storm control to prevent broadcast, multicast, and unknown unicast traffic from overwhelming access links. Where is storm-control applied in the Junos configuration hierarchy?

Accepted Answer

set interfaces ge-0/0/1 unit 0 family ethernet-switching storm-control. Storm control is applied under 'interfaces <interface-name> unit 0 family ethernet-switching storm-control'.

Answer

set vlans default storm-control

Answer

set protocols l2-learning storm-control interface ge-0/0/1

Answer

set forwarding-options storm-control interface ge-0/0/1

Question 18

Which TWO actions can be triggered when a MAC address limit is exceeded on a Juniper switch interface configured with MAC limiting? (Choose two)

Accepted Answer

drop. Configurable actions on MAC limit violation include drop and log, or drop and shutdown (disable) the interface.

Answer

quarantine

Answer

reboot

Answer

isolate-vlan

Question 19

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 20

Which TWO parameters can be configured within a Junos scheduler definition? (Choose two)

Accepted Answer

transmit-rate. Schedulers include parameters such as transmit-rate, buffer-size, priority, and drop-profile-map.

Answer

rewrite-rule

Answer

bandwidth-limit

Answer

policer-action