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JNCIP-ENT practice questions

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Question 1Interior Gateway Protocols (IGPs)

In Junos OS, which protocol is enabled by default on all interfaces when you configure an interface address in a Juniper device running the default configuration?

  1. IS-IS
  2. RIP
  3. OSPF Correct answer.
  4. BGP

Explanation

Junos OS enables OSPF by default on interfaces where an address is configured when the default configuration is loaded, provided the interface is not explicitly excluded. IS-IS, RIP, and BGP are not enabled by default and require explicit configuration. This default behavior is a common source of unexpected adjacencies.

Question 2Interior Gateway Protocols (IGPs)

A Junos device has two OSPF areas configured. Which area must exist for OSPF to function as a transit backbone between other areas?

  1. Area 0.0.0.1
  2. Area 1
  3. Area 0 Correct answer.
  4. Area 255

Explanation

OSPF requires a backbone area, which is always area 0 (0.0.0.0). All other areas must connect to the backbone either directly or through a virtual link. Area 1 and area 0.0.0.1 are normal non-backbone areas, and area 255 is not a special reserved area in OSPF.

Question 3Interior Gateway Protocols (IGPs)

Which IS-IS PDU type is used to establish and maintain point-to-point adjacencies between two routers?

  1. Level 2 LAN IIH
  2. Level 1 LAN IIH
  3. Point-to-Point IIH Correct answer.
  4. Complete Sequence Number PDU

Explanation

Point-to-Point IIH PDUs are used on point-to-point links to form and maintain adjacencies. LAN IIH PDUs are used on broadcast multiaccess networks, and CSNPs are used to synchronize the link-state database, not to establish adjacencies.

Question 4Interior Gateway Protocols (IGPs)

In OSPF, which router type generates Type 4 summary ASBR LSAs within a non-backbone area?

  1. The designated router on each segment
  2. Any internal router in the area
  3. The ASBR itself
  4. The area border router for that area Correct answer.

Explanation

The area border router originates Type 4 summary LSAs to advertise the reachability of an ASBR to routers inside a non-backbone area. Internal routers and the designated router do not generate Type 4 LSAs. The ASBR itself originates Type 5 external LSAs, not Type 4.

Question 5Interior Gateway Protocols (IGPs)

What is the default OSPF hello interval on a Junos interface whose OSPF interface type is p2p?

  1. 120 seconds
  2. 40 seconds
  3. 30 seconds
  4. 10 seconds Correct answer.

Explanation

On point-to-point OSPF interfaces, the default hello interval is 10 seconds, matching the default for broadcast interfaces. The 30-second default applies to non-broadcast multiaccess interfaces. The dead interval defaults to four times the hello interval.

Question 6Interior Gateway Protocols (IGPs)

Which IS-IS metric style does Junos OS use by default on a device configured for IS-IS?

  1. Both narrow and wide metrics
  2. Transition metrics
  3. Narrow metrics only
  4. Wide metrics only Correct answer.

Explanation

Junos OS enables wide metrics by default, which supports 24-bit interface metrics and TLVs needed for traffic engineering and IPv6. Narrow metrics are the older 6-bit style and must be explicitly configured if required. Transition mode is used only to interoperate with narrow-only devices.

Question 7Interior Gateway Protocols (IGPs)

A network engineer wants to summarize OSPF inter-area routes advertised from area 1 into the backbone. Where must the summary be configured?

  1. On the ASBR in area 1
  2. On every internal router in area 1
  3. On the area border router under area 0
  4. On the area border router under area 1 Correct answer.

Explanation

Inter-area summarization is configured on the area border router under the source area with the area-range statement. The ABR then advertises a single Type 3 summary LSA into the backbone. Configuring it under area 0 or on internal routers does not summarize routes from area 1.

Question 8Interior Gateway Protocols (IGPs)

Which statement about OSPF router priority on a Junos broadcast interface is correct?

  1. A priority of 0 makes the router ineligible to become DR or BDR Correct answer.
  2. Higher priority values make a router less likely to become DR
  3. Priority must be identical on all routers in the area
  4. Priority is only used on point-to-point interfaces

Explanation

Setting OSPF priority to 0 prevents a router from being elected designated router or backup designated router. Higher priority values increase the chance of election, and priority is relevant on broadcast and NBMA networks, not point-to-point links. Priorities may differ between routers.

Question 9Interior Gateway Protocols (IGPs)

An engineer configures an OSPF virtual link across a non-backbone area to connect a remote area to area 0. Which two routers must the virtual link be configured on?

  1. The ASBR and the backbone DR
  2. The two internal routers in the transit area
  3. The designated routers of the transit area
  4. The two area border routers that share the transit area Correct answer.

Explanation

A virtual link is configured between two area border routers that both have an interface in the transit area and one in area 0. It is not configured on internal routers or designated routers. The link is treated as an unnumbered point-to-point connection in area 0.

Question 10Interior Gateway Protocols (IGPs)

Which IS-IS feature prevents a router from installing a route through itself when it receives its own LSP during flooding?

  1. Sequence number aging
  2. The overload bit
  3. The attached bit
  4. The split horizon check Correct answer.

Explanation

IS-IS performs a split horizon check so a router ignores routing information it originated when computing the SPF tree. The overload bit marks a router as unusable for transit but does not perform this loop prevention. The attached bit signals L1-to-L2 connectivity, and sequence aging manages LSP lifetime.

Question 11Interior Gateway Protocols (IGPs)

A Junos router runs OSPF and receives the same prefix from an intra-area route, an inter-area route, and an external Type 2 route. Which route does OSPF prefer?

  1. The external Type 2 route
  2. The route with the lowest interface metric regardless of type
  3. The inter-area route
  4. The intra-area route Correct answer.

Explanation

OSPF prefers intra-area routes over inter-area routes, and both over external routes. Among external routes, Type 1 is preferred over Type 2. Interface metric alone does not override the route-type preference order.

Question 12Interior Gateway Protocols (IGPs)

Which OSPF LSA type carries information about a multiaccess network and its attached routers, and is originated by the designated router?

  1. Type 5 AS External LSA
  2. Type 1 Router LSA
  3. Type 2 Network LSA Correct answer.
  4. Type 3 Summary LSA

Explanation

The Type 2 Network LSA is generated by the designated router and lists all routers attached to the multiaccess segment. Type 1 Router LSAs describe individual routers, Type 3 summarizes inter-area prefixes, and Type 5 carries external routes.

Question 13Interior Gateway Protocols (IGPs)

A network uses IS-IS with Level 1 and Level 2 routing. Which statement describes how a Level 1 router reaches a destination outside its area?

  1. It forms a direct adjacency with the destination area's Level 2 router
  2. It floods Type 5 external LSAs throughout Level 1
  3. It installs a default route toward the nearest Level 1-2 router Correct answer.
  4. It runs a full SPF on the Level 2 database

Explanation

Level 1 routers do not maintain the Level 2 database; they install a default route toward the closest Level 1-2 router, indicated by the attached bit. They do not run Level 2 SPF or form direct Level 2 adjacencies. IS-IS does not use Type 5 LSAs.

Question 14Interior Gateway Protocols (IGPs)

Which configuration enables OSPF authentication using MD5 on a Junos interface?

  1. set protocols ospf area 0 interface ge-0/0/0.0 authentication hmac-sha-256 secret
  2. set protocols ospf area 0 interface ge-0/0/0.0 authentication simple-password secret
  3. set protocols ospf area 0 interface ge-0/0/0.0 authentication md5 1 key secret Correct answer.
  4. set protocols ospf area 0 interface ge-0/0/0.0 authentication key-chain secret

Explanation

Junos OSPF MD5 authentication is configured with the authentication md5 key-id key syntax under the interface. Simple-password enables plaintext authentication, and key-chain references a configured key chain. HMAC-SHA-256 is not an OSPF interface authentication option in this form.

Question 15Interior Gateway Protocols (IGPs)

A router redistributes static routes into OSPF. Which LSA type is generated by default on the ASBR for these routes?

  1. Type 3
  2. Type 2
  3. Type 5 Correct answer.
  4. Type 1

Explanation

Redistributed external routes are carried in Type 5 AS External LSAs originated by the ASBR. Type 1 and Type 2 LSAs describe intra-area topology, and Type 3 LSAs are generated by ABRs for inter-area routes. A stub area would suppress Type 5 LSAs, but that is not the default.

Question 16Interior Gateway Protocols (IGPs)

Which IS-IS configuration places a router in both Level 1 and Level 2 routing on a Junos device?

  1. set protocols isis level 1 disable
  2. set protocols isis level 2 disable
  3. set protocols isis level 1-2 Correct answer.
  4. set protocols isis interface ge-0/0/0.0 level 1 disable

Explanation

The level 1-2 statement configures the router to operate as both a Level 1 and Level 2 router. Disabling level 1 or level 2 restricts the router to a single level, and disabling a level on an interface affects only that interface.

Question 17Interior Gateway Protocols (IGPs)

Which OSPF area type blocks Type 5 external LSAs but allows Type 3 summary LSAs?

  1. Stub area Correct answer.
  2. Totally stubby area
  3. Normal area
  4. Not-so-stubby area

Explanation

A stub area blocks Type 5 external LSAs while still allowing Type 3 summary LSAs from the ABR. A totally stubby area additionally blocks Type 3 LSAs except a default. An NSSA allows external LSAs in a limited Type 7 form, and a normal area allows all LSAs.

Question 18Interior Gateway Protocols (IGPs)

A Junos device has an OSPF interface with a dead interval of 40 seconds. What hello interval is implied by the default relationship?

  1. 4 seconds
  2. 20 seconds
  3. 40 seconds
  4. 10 seconds Correct answer.

Explanation

OSPF sets the dead interval to four times the hello interval by default, so a 40-second dead interval corresponds to a 10-second hello. The other values do not satisfy the 4:1 default relationship. Both timers must match on neighbors for adjacency to form.

Question 19Interior Gateway Protocols (IGPs)

Which statement about IS-IS pseudonode LSPs on a broadcast network is correct?

  1. Pseudonode LSPs are used only on point-to-point links
  2. The DIS generates one pseudonode LSP per neighbor adjacency
  3. The designated intermediate system generates a pseudonode LSP representing the LAN Correct answer.
  4. Each router generates a pseudonode LSP for its own interface

Explanation

On a broadcast network, the designated intermediate system creates a pseudonode LSP that represents the multiaccess segment as a virtual node. Individual routers reference the pseudonode in their own LSPs rather than creating their own pseudonode LSP. Pseudonode LSPs are not used on point-to-point links.

Question 20Interior Gateway Protocols (IGPs)

A network engineer needs OSPF to advertise a default route into a stub area. Which approach accomplishes this on the area border router?

  1. Configure an export policy that matches 0.0.0.0/0
  2. Configure default-metric on the ABR
  3. Configure a static default route and redistribute it into OSPF
  4. Configure the stub area with the default-metric option Correct answer.

Explanation

On the ABR, configuring the stub area with default-metric causes the ABR to inject a default summary LSA into the stub area. Redistribution and export policies generate Type 5 LSAs, which are not allowed in a stub area. The default-metric statement alone does not inject a default route.

Question 21Interior Gateway Protocols (IGPs)

Two Junos routers connected over a point-to-point link fail to form an OSPF adjacency. The interfaces are up and addresses are correct, but the hello packets are rejected. Which mismatch is the most likely cause?

  1. Different interface MTU sizes
  2. Different area IDs on the interfaces Correct answer.
  3. Different loopback addresses
  4. Different OSPF router IDs

Explanation

OSPF hello packets must agree on area ID, hello and dead intervals, authentication, and stub flags for an adjacency to form. Router IDs and loopback addresses may differ legitimately. An MTU mismatch typically affects database exchange rather than hello acceptance.

Question 22Interior Gateway Protocols (IGPs)

In IS-IS, which TLV in a router's LSP advertises the list of IP prefixes reachable through that router?

  1. TLV 135 (Extended IP Reachability) Correct answer.
  2. TLV 10 (Authentication)
  3. TLV 1 (Area Addresses)
  4. TLV 22 (Extended IS Reachability)

Explanation

TLV 135 carries extended IP reachability information, listing prefixes and their metrics. TLV 22 describes IS neighbor reachability rather than IP prefixes, TLV 1 carries area addresses, and TLV 10 carries authentication data.

Question 23Interior Gateway Protocols (IGPs)

A Junos router is configured as an OSPF ABR between area 0 and area 1. Area 1 is configured as totally stubby. Which LSAs does the ABR inject into area 1?

  1. Type 7 externals plus a default summary
  2. Type 3 summaries for all area 0 prefixes plus a default summary
  3. Type 5 externals plus a default summary
  4. Only a default summary LSA Correct answer.

Explanation

A totally stubby area receives only a default summary LSA from the ABR, with all other Type 3 summaries and Type 5 externals suppressed. It does not receive individual Type 3 summaries for area 0 prefixes. Type 5 externals are blocked, and Type 7 LSAs are used only in NSSAs.

Question 24Interior Gateway Protocols (IGPs)

An engineer observes that an IS-IS router sets the overload bit during startup. What is the effect of this setting?

  1. The router is excluded from transit paths until the bit is cleared Correct answer.
  2. The router prefers Level 2 routes over Level 1 routes
  3. The router drops all Level 1 adjacencies
  4. The router stops generating its own LSPs

Explanation

When the overload bit is set, other routers do not use the advertising router as a transit hop in SPF calculations, though directly connected prefixes remain reachable. The bit does not tear down adjacencies, stop LSP generation, or change level preference. Junos can set the bit temporarily during startup to avoid black-holing traffic.

Question 25Interior Gateway Protocols (IGPs)

A Junos router runs OSPF and IS-IS for the same prefixes. By default, which route is installed when the OSPF and IS-IS routes have equal preference values?

  1. Both routes are installed and load-balanced
  2. The route with the lower metric, regardless of protocol
  3. The IS-IS route, because IS-IS has a lower default preference Correct answer.
  4. The OSPF route, because OSPF has a lower default preference

Explanation

Junos assigns IS-IS a default preference of 15 and OSPF a default preference of 10, so an OSPF route is normally preferred. However, when preferences are equalized, Junos uses the lower metric, and if metrics also match, IS-IS is preferred over OSPF by the internal protocol preference order. This behavior is relevant when engineers deliberately equalize preferences for migration.

Question 26BGP

On a Junos device, which BGP attribute is recognized by all BGP implementations and must be propagated to every BGP speaker, and therefore is never included in a route's attribute set that can be discarded?

  1. AS path Correct answer.
  2. Local preference
  3. MED
  4. Originator ID

Explanation

The AS path is a well-known mandatory attribute, so every BGP speaker must recognize it and include it in updates to peers. Local preference is well-known discretionary, while MED and originator ID are optional attributes.

Question 27BGP

A Junos router receives the same prefix from two external peers with identical AS path lengths. By default, which tie-breaker does Junos apply first in the BGP decision process?

  1. Highest local preference Correct answer.
  2. Lowest origin code
  3. Lowest MED
  4. Lowest router ID of the peer

Explanation

Junos evaluates local preference before AS path length and MED, so a higher local preference wins even before path length is compared. The peer router ID is consulted only after many other attributes tie.

Question 28BGP

Which BGP message type is used to advertise new prefixes and withdraw previously advertised ones between peers?

  1. NOTIFICATION
  2. KEEPALIVE
  3. UPDATE Correct answer.
  4. OPEN

Explanation

The UPDATE message carries path attributes and NLRI for new or changed routes, and withdrawn routes for prefixes no longer reachable. OPEN negotiates session parameters, KEEPALIVE maintains the session, and NOTIFICATION reports errors.

Question 29BGP

A Junos router is configured with a BGP group that has type external and a peer-as of 65001. What does this configuration establish?

  1. An IBGP session within AS 65001
  2. An EBGP session with a peer in AS 65001 Correct answer.
  3. A confederation sub-AS session
  4. A route reflector client relationship

Explanation

The type external statement makes the session EBGP, and peer-as 65001 identifies the remote autonomous system. The local AS must differ from the peer AS for an EBGP session to come up.

Question 30BGP

Which statement describes the purpose of the BGP next-hop attribute in Junos?

  1. It specifies the IP address to reach the prefix and must be resolvable in the routing table Correct answer.
  2. It sets the preference used to compare routes from different peers
  3. It carries the accumulated list of ASes the route traversed
  4. It identifies the AS that originated the prefix

Explanation

The next hop tells the receiving router where to forward traffic for the prefix, and BGP requires that address to be resolvable through the IGP or a connected route. Unresolvable next hops cause the route to be hidden.

Question 31BGP

What is the default value of local preference on a Junos router for routes learned from BGP peers?

  1. 65535
  2. 100 Correct answer.
  3. 32768
  4. 0

Explanation

Junos assigns a default local preference of 100 to BGP routes unless a routing policy sets a different value. Higher local preference is preferred during the decision process.

Question 32BGP

Which Junos command displays the BGP routes received from a specific neighbor in summary form?

  1. show route receive-protocol bgp <neighbor> Correct answer.
  2. show route protocol bgp detail
  3. show bgp neighbor
  4. show bgp summary

Explanation

The show route receive-protocol bgp command lists the routes a specific neighbor advertised before import policy is applied. This helps verify what was received versus what was accepted.

Question 33BGP

A network engineer wants routes learned from an EBGP peer to be preferred over identical routes from another EBGP peer. Which attribute should the policy modify?

  1. Local preference Correct answer.
  2. Origin
  3. MED
  4. Atomic aggregate

Explanation

Local preference is the standard attribute for expressing preference among multiple exit points within a single AS. Setting a higher local preference on routes from the preferred peer makes them win the decision process.

Question 34BGP

A Junos router has two EBGP peers advertising the same prefix. One peer sends the route with an AS path of 65001 65002, and the other sends it with an AS path of 65001 65002 65003. Assuming all other attributes tie, which route is selected?

  1. The route with the longer AS path
  2. The route with the highest origin code
  3. The route with the lowest peer router ID
  4. The route with the shorter AS path Correct answer.

Explanation

Junos prefers the shortest AS path when other earlier attributes tie, because a shorter path usually means fewer autonomous systems to traverse. The two-AS path wins over the three-AS path.

Question 35BGP

Which configuration enables BGP on a Junos router and assigns it to the global autonomous system 65010?

  1. set protocols bgp local-as 65010
  2. set routing-options autonomous-system 65010 Correct answer.
  3. set protocols bgp group EBGP peer-as 65010
  4. set routing-options router-id 65010

Explanation

The autonomous-system statement under routing-options defines the local AS used by all routing protocols. BGP groups then reference this AS automatically.

Question 36BGP

A Junos router running IBGP receives a route from an IBGP peer and needs to forward it to another IBGP peer. What does the split-horizon rule for IBGP require?

  1. The route is not advertised to the other IBGP peer Correct answer.
  2. The route is advertised to the other IBGP peer unchanged
  3. The route is advertised only after the next hop is changed to self
  4. The route is advertised only if it was learned from a route reflector

Explanation

IBGP does not re-advertise routes learned from one IBGP peer to another to prevent routing loops within the AS. Full mesh peering, route reflection, or confederations are used to achieve full reachability.

Question 37BGP

A route reflector is configured with cluster ID 10.10.10.10 and has three clients in the same cluster. When the reflector receives a route from one client, to which peers does it forward the route?

  1. To no peers because the route came from a client
  2. Only to non-client peers
  3. Only to the other clients in the cluster
  4. To all non-client peers and the other clients in the cluster Correct answer.

Explanation

A route reflector reflects routes from a client to all other clients and to all non-client IBGP peers, while avoiding sending back to the originator. This preserves reachability without a full mesh.

Question 38BGP

What is the purpose of the originator ID attribute in a route reflector environment?

  1. It carries the local preference of the reflector
  2. It identifies the reflector that last forwarded the route
  3. It identifies the cluster in which the route was reflected
  4. It identifies the original advertising router to prevent loops Correct answer.

Explanation

The originator ID records the router ID of the router that first injected the route into the AS, allowing the reflector to detect and drop routes that loop back. The cluster list performs a similar loop-prevention role for clusters.

Question 39BGP

A Junos router uses a BGP export policy that accepts only routes matching a prefix list. What happens to routes that do not match the prefix list?

  1. They are rejected and not advertised Correct answer.
  2. They are converted to static routes
  3. They are advertised with a MED of 0
  4. They are advertised to peers

Explanation

An export policy controls which routes are advertised to BGP peers, and a route that does not match any accepting term is not advertised. Routes remain in the routing table but are suppressed from the update.

Question 40BGP

Which BGP attribute is nontransitive and is used to influence how traffic enters an AS from a neighboring AS?

  1. Local preference
  2. AS path
  3. MED Correct answer.
  4. Next hop

Explanation

MED is an optional nontransitive attribute that suggests a preferred entry point into an AS, so it is typically used to influence inbound traffic. Because it is nontransitive, it is not propagated beyond the neighboring AS by default.

Question 41BGP

A Junos router receives a route with the BGP community 65000:100. Which configuration is required to match this community in a policy?

  1. A community member definition referencing 65000:100 Correct answer.
  2. A prefix list containing the community value
  3. An AS path regular expression matching 65000:100
  4. A route filter matching the community string

Explanation

Junos requires communities to be defined with the community statement under policy-options before a policy term can match them. The policy then references the defined member by name.

Question 42BGP

Which statement about EBGP multihop on Junos is correct?

  1. It automatically sets the next hop to self
  2. It allows IBGP sessions to use multiple hops
  3. It disables the TTL check for IBGP sessions
  4. It allows an EBGP session to be established between peers that are not directly connected Correct answer.

Explanation

EBGP multihop permits an external session to form when the peers are separated by intervening routers, such as when peering to a loopback address. The configuration also requires a next-hop policy to accept the non-directly connected address.

Question 43BGP

A Junos router peers with an external neighbor over a loopback interface. Which two configuration elements are typically needed for the session to come up and routes to be usable? (Choose the best answer.)

  1. local-as and a confederation ID
  2. peer-as and a route reflector cluster
  3. passive and a hold-time of 0
  4. multihop and a next-hop policy Correct answer.

Explanation

Peering to a loopback requires multihop because the peers are not directly connected, and a next-hop policy is needed so that the received next hop is accepted. Without the next-hop policy, routes may be hidden as unresolvable.

Question 44BGP

What does the BGP route damping feature do on a Junos router?

  1. It converts BGP routes into OSPF routes
  2. It load-balances traffic across multiple paths
  3. It suppresses routes that flap frequently by assigning a penalty Correct answer.
  4. It encrypts BGP updates between peers

Explanation

Route damping assigns a penalty each time a route is withdrawn and suppresses the route when the penalty exceeds a threshold. The penalty decays over time, and the route is reused once it falls below the reuse limit.

Question 45BGP

A Junos router has two paths to the same prefix with equal local preference, AS path, origin, and MED. The first path has an IGP cost of 10 and the second has an IGP cost of 20. Which path is preferred?

  1. The path with the higher peer router ID
  2. The path with IGP cost 10 Correct answer.
  3. The path with IGP cost 20
  4. The path with the lower peer router ID

Explanation

When earlier attributes tie, Junos prefers the path with the lower IGP metric to the next hop. The path with cost 10 wins before router ID is considered.

Question 46BGP

Which BGP capability allows a router to carry IPv6 prefixes over a session established with IPv4 addresses?

  1. 4-byte AS number support
  2. Graceful restart
  3. Multiprotocol BGP Correct answer.
  4. Route refresh

Explanation

Multiprotocol BGP extensions allow a session to negotiate address families independently of the transport address. This lets an IPv4 peering carry IPv6 NLRI using the inet6 family.

Question 47BGP

A Junos router receives a route with an AS path that already contains its own AS number. What does the router do by default?

  1. It strips its own AS from the path and accepts it
  2. It sets the route's MED to 0 and accepts it
  3. It accepts the route and installs it
  4. It rejects the route as a loop Correct answer.

Explanation

BGP loop prevention rejects any route whose AS path contains the local AS number, because that indicates the route has already traversed this AS. The route is discarded before it can be installed.

Question 48BGP

A route reflector receives a route that carries a cluster list containing its own cluster ID. What action does the reflector take?

  1. It discards the route to prevent a reflection loop Correct answer.
  2. It converts the route to an IBGP route with a new originator ID
  3. It reflects the route to all clients
  4. It appends its cluster ID again and reflects the route

Explanation

The cluster list records the clusters a reflected route has traversed, and a reflector drops any route whose cluster list already contains its own cluster ID. This prevents routing loops between redundant reflectors.

Question 49BGP

A Junos router uses a policy to prepend its AS number three times to routes advertised to a specific EBGP peer. What is the primary effect of this configuration?

  1. It forces the peer to use a specific next hop
  2. It increases the local preference of routes received from the peer
  3. It reduces the MED advertised to the peer
  4. It makes the local AS appear farther away to that peer's AS path selection Correct answer.

Explanation

AS path prepending lengthens the AS path seen by the receiving AS, making the path less attractive when that AS compares paths. It is a common technique for influencing inbound traffic.

Question 50BGP

A Junos router has an IBGP session with a peer that is two hops away through an IGP. Which statement explains why the session can still come up without multihop configuration?

  1. IBGP sessions use a TTL of 255 and do not require directly connected peers
  2. IBGP sessions automatically enable multihop
  3. IBGP sessions rely on the IGP to resolve the peer address Correct answer.
  4. IBGP sessions use a TTL of 1 by default

Explanation

IBGP peers are typically reached through loopback addresses resolved by the IGP, so the session does not require direct connectivity. The default TTL for IBGP is 255, allowing multi-hop reachability without an explicit multihop statement.