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JNCIS-ENT · domain

BGP

Practise Juniper Networks Enterprise Routing and Switching, Specialist (JNCIS-ENT, JN0-352) (JNCIS-ENT) BGP practice questions — original exam-style scenarios with answer choices, explanations, and analysis of common mistakes.

56 questions10 easy26 medium20 hard

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What this domain covers

What to know about BGP

BGP questions usually test path selection attributes (AS-PATH, LOCAL_PREF, MED), eBGP vs iBGP rules, and why a route may be received but not used.

BGP path selection order: weight, LOCAL_PREF, origin, AS-PATH, MED.

eBGP vs iBGP peering rules and TTL requirements.

How route reflectors and confederations solve iBGP full-mesh requirements.

Why a route may appear in the BGP table but not be the best path.

Watch out for

Common BGP exam traps

  • BGP does not automatically advertise connected routes — network statements or redistribution are required.
  • iBGP peers do not increment AS-PATH; eBGP peers do.
  • LOCAL_PREF is used within an AS; MED is used between ASes.
  • A route being received does not mean it will be installed in the routing table.

Question index

All BGP questions (56)

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1

An administrator wants to modify the Local Preference attribute for all routes received from a specific external BGP peer. Where must this policy be applied in Junos?

Easy
2

Which TWO characteristics describe eBGP compared to iBGP? (Choose two)

Medium
3

An administrator is configuring eBGP between two Junos devices and notices the session is stuck in the Active state. The direct connection is up, and ping succeeds. Which Junos configuration parameter is most likely missing to resolve this issue?

Medium
4

A Junos router receives four identical routes via BGP. Reviewing the routing table, path selection picked route 3. Route 1 has a lower MED, Route 2 has a higher Local Preference, Route 4 is from an eBGP peer while Route 3 is iBGP. Assuming standard default path selection, why was Route 3 chosen over Route 4?

Hard
5

Which THREE statements describe the role and function of the BGP Router ID? (Choose three)

Hard
6

During troubleshooting of a flapping BGP session, you notice BGP Notification messages being sent. Which BGP message type is responsible for tearing down a session due to an error condition?

Medium
7

When troubleshooting a BGP routing loop or unexpected route suppression, which THREE Junos operational commands provide visibility into BGP path attributes and decision processes? (Choose three)

Hard
8

A network operator needs to peer two routers in different Autonomous Systems that are not directly connected. Security policy mandates that TTL security checks be bypassed. Which command satisfies this requirement for the BGP session?

Medium
9

What is the purpose of the BGP Keepalive message and what is its default interval in Junos?

Medium
10

When evaluating the BGP path selection algorithm on a Junos device, which THREE attributes are evaluated BEFORE the router considers the IGP metric to the BGP next hop? (Choose three)

Hard
11

An administrator implements an inbound policy to discard BGP routes matching a specific community. Which action statement is required in the policy term?

Medium
12

Which THREE path attributes are classified as 'well-known mandatory'? (Choose three)

Hard
13

An administrator configures a BGP policy to reject routes with an AS_PATH containing a specific AS number. Which match condition in a Junos routing policy is used to evaluate the AS_PATH?

Easy
14

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

Medium
15

Which BGP message type is responsible for negotiating session parameters, including autonomous system numbers, hold times, and BGP identifiers during session establishment?

Hard
16

You need to ensure that an iBGP-learned route is properly advertised to other eBGP peers without triggering routing loops. Which mechanism does BGP use automatically to prevent routing loops within an Autonomous System?

Medium
17

An administrator is troubleshooting a BGP peering session that is stuck in the Connect or Active state. Which THREE common causes could explain this issue? (Choose three)

Hard
18

An MX Series router is configured with BGP Multipath. Two paths have identical Local Preference, AS path length, origin, and MED. Which additional configuration statement is required under protocols bgp to enable multipath load balancing across these iBGP paths?

Hard
19

Which TWO BGP message types are responsible for maintaining session state or reporting errors without carrying routing information? (Choose two)

Medium
20

While examining a BGP routing table, you notice a route with an ORIGIN attribute set to 'Incomplete'. What does this indicate about the origin of the route?

Hard
21

An engineer is troubleshooting a BGP session between two routers and notices that the connection is stuck in the Active state. What does the Active state indicate about the BGP finite state machine?

Easy
22

A Junos router is configured as a BGP route reflector. It learns a route from a client and reflects it to a non-client and another client. Which attribute does the route reflector modify or add to prevent routing loops?

Hard
23

Which BGP attribute is classified as 'well-known discretionary'?

Medium
24

Which TCP port is used by BGP to establish communication between peers?

Easy
25

A network administrator needs to modify the Local Preference path attribute for all routes received from a specific external BGP peer using a routing policy on Junos. Under which configuration hierarchy should the routing policy be applied?

Medium
26

What is the primary function of the BGP OPEN message?

Medium
27

A network engineer configures BGP confederations to scale an enterprise network. Which BGP path attribute is stripped or modified when an update leaves a sub-AS within the confederation and enters another sub-AS?

Hard
28

When a Junos router establishes an eBGP session, what is the default value of the Local Preference attribute assigned to incoming routes if not modified by a policy?

Easy
29

Which THREE actions occur when a BGP speaker receives a Notification message from a peer? (Choose three.)

Hard
30

You are running BGP between two routers. One router has a 4-byte ASN (e.g., ASN 65536). The remote router only supports 2-byte ASNs. How does BGP handle this compatibility issue?

Hard
31

Which TWO statements describe characteristics of BGP path attributes? (Choose two.)

Medium
32

You notice that an iBGP peer is not advertising routes it learned from an eBGP peer to other iBGP peers. What architectural rule explains this behavior?

Medium
33

You need to ensure that BGP sessions fail over within sub-second intervals if a link degrades or goes down. Which protocol should you integrate with BGP on your Junos router?

Medium
34

You need to configure an explicit export policy in Junos so that your eBGP router only advertises locally originated routes and refuses to transit third-party routes. Which AS_PATH regular expression accomplishes this?

Medium
35

An engineer must inspect the BGP state and verify the received prefix counts from a specific neighbor on an MX Series router. Which operational command should be used?

Easy
36

An engineer configures iBGP peering between two routers in the same AS. Route reflection is not used. The engineer notices that routes learned from an eBGP peer by Router A are not being advertised by Router A to Router B (its iBGP peer). Why is this happening?

Medium
37

An engineer needs to verify which BGP routes are currently installed in the forwarding table (FIB). Which command should be used?

Easy
38

A BGP speaker receives an UPDATE message containing a malformed attribute. According to BGP specifications, which action does the receiving router take?

Hard
39

An enterprise customer connects to two different service providers via eBGP. They want to preferentially use Service Provider A, but fail over to Service Provider B if Provider A fails. How can they influence the inbound traffic from the providers?

Hard
40

Which TWO statements are true regarding BGP communities in Junos? (Choose two)

Medium
41

Which TWO actions occur when a Junos BGP routing policy includes the 'next policy' action? (Choose two)

Medium
42

An administrator configures BGP multipath on a Junos router. Which THREE conditions must be met for BGP paths to be considered equal and installed as multipaths? (Choose three)

Hard
43

A network engineer configures an eBGP session on a Junos device and notices that routes learned from the external peer are not being installed in the routing table or advertised to other peers. What is the default behavior regarding eBGP route propagation and next-hop resolution on Junos OS?

Medium
44

An operator troubleshooting BGP path selection notices two routes have identical Local Preference, AS path length, origin, MED, and both are eBGP routes. Which attribute does the BGP path selection algorithm evaluate next?

Hard
45

While reviewing BGP updates, you notice an attribute type code of 3 with a value representing an IP address. Which well-known mandatory path attribute is this?

Hard
46

Which TWO statements accurately describe the behavior of the BGP AS_PATH attribute? (Choose two)

Medium
47

Which command allows an administrator to view real-time BGP routing updates being sent and received on a Junos device?

Easy
48

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?

Medium
49

An administrator needs to verify the exact BGP timers negotiated with an eBGP peer on a Junos device. Which operational command should be used?

Easy
50

An engineer configures a BGP policy to set the MED attribute on routes advertised to an eBGP peer. What is the primary purpose of the MED (Multi-Exit Discriminator) attribute?

Medium
51

You are troubleshooting a route leak between two eBGP peers. You notice that an incoming route contains your own ASN in the AS_PATH attribute, yet the route was installed. Which Junos feature allowed this behavior, and where is it configured?

Medium
52

Which THREE attributes are optional transitive BGP path attributes? (Choose three)

Hard
53

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?

Easy
54

Which TWO statements correctly differentiate eBGP from iBGP? (Choose two.)

Medium
55

Which TWO BGP attributes are strictly internal to an Autonomous System and are never advertised to external eBGP peers? (Choose two)

Medium
56

During BGP path selection on a Junos device, two paths are received for the same destination prefix. Path A has a MED of 50 received from a peer in AS 65001, and Path B has a MED of 10. Both AS paths have a length of 2. The router is not configured with 'always-compare-med'. Which path will be preferred by default?

Hard

Frequently asked questions

What does the BGP domain cover on the JNCIS-ENT exam?
BGP questions usually test path selection attributes (AS-PATH, LOCAL_PREF, MED), eBGP vs iBGP rules, and why a route may be received but not used.
How many questions are in this domain?
This page lists all 56 BGP questions in the JNCIS-ENT question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
What is the best way to practise this domain?
Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
Can I practise only BGP questions?
Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.
juniper-jncis-ent JUNIPER-JNCIS-ENT bgp Practice Questions