View Full Juniper JN0-364  Exam Dumps and Practice Test Dumps

Question: 321. Which OSPF mechanism is responsible for calculating the shortest path through the link-state database?

1. BGP path selection
   2. Dijkstra’s Shortest Path First algorithm
   3. LACP negotiation
   4. RIP hop-count calculation

Correct Answer: 2. Dijkstra’s Shortest Path First algorithm

Explanation:

OSPF uses Dijkstra’s Shortest Path First (SPF) algorithm to calculate the shortest paths through its link-state database. Each router builds a topology view from LSAs and then runs SPF to determine the best paths to destinations. The resulting routes can be installed in the routing table. BGP uses a different path-selection process based on attributes, RIP uses hop count as its primary metric, and LACP negotiates link aggregation rather than calculating Layer 3 paths.

Question: 322. Which BGP attribute is generally preferred when comparing routes received from different external paths for outbound traffic within an autonomous system?

1. Local Preference
   2. MED
   3. AS_PATH
   4. Origin

Correct Answer: 1. Local Preference

Explanation:

BGP Local Preference is used inside an autonomous system to influence the preferred exit point for outbound traffic. A higher Local Preference value is generally preferred when comparing eligible BGP routes. Network administrators commonly use routing policy to assign different Local Preference values to routes received from different external connections. MED instead provides information that can influence how a neighboring AS selects an entry point, while AS_PATH and Origin are different BGP path attributes used at other stages of route selection.

Question: 323. What is the primary purpose of an OSPF Designated Router on a broadcast multiaccess network?

1. To assign IPv4 addresses to hosts
   2. To replace the routing table
   3. To reduce the number of OSPF adjacencies and LSA flooding relationships
   4. To provide BGP route reflection

Correct Answer: 3. To reduce the number of OSPF adjacencies and LSA flooding relationships

Explanation:

On broadcast multiaccess networks, OSPF elects a Designated Router (DR) to reduce the number of full adjacencies required between routers. Without a DR, every router could need a direct adjacency with every other router, creating significant overhead as the number of routers increases. The DR acts as a central point for certain OSPF database exchange and flooding operations. The Backup Designated Router (BDR) provides redundancy if the DR fails. DR functionality is specific to OSPF and is unrelated to BGP route reflection.

Question: 324. Which Junos routing table is normally used for IPv6 unicast routes?

1. inet.0
   2. inet6.0
   3. mpls.0
   4. iso.0

Correct Answer: 2. inet6.0

Explanation:

In Junos, the inet6.0 routing table is the primary routing table for IPv6 unicast routes. The inet.0 table is used for IPv4 unicast routes. Other routing tables are associated with different protocol families or forwarding functions. Understanding the distinction between inet.0 and inet6.0 is important when troubleshooting IPv4 and IPv6 routing because a route installed in one table does not automatically appear in the other.

Question: 325. Which protocol is commonly used to provide first-hop gateway redundancy between routers?

1. VRRP
   2. BFD
   3. LACP
   4. IS-IS

Correct Answer: 1. VRRP

Explanation:

VRRP, or Virtual Router Redundancy Protocol, provides first-hop gateway redundancy by allowing multiple routers to participate in a virtual router group. Hosts can use a virtual IP address as their default gateway while one router performs the active forwarding role and another can take over if needed. BFD provides rapid failure detection, LACP provides link aggregation, and IS-IS is a link-state routing protocol. VRRP therefore addresses gateway availability rather than routing-protocol path calculation or physical-link aggregation.

Question: 326. Which BGP attribute records the sequence of autonomous systems through which a route advertisement has passed?

1. NEXT_HOP
   2. MED
   3. AS_PATH
   4. Local Preference

Correct Answer: 3. AS_PATH

Explanation:

The AS_PATH attribute contains the sequence of autonomous system numbers that a BGP route advertisement has traversed. Besides providing path information, AS_PATH is an important loop-prevention mechanism. When a BGP router detects its own AS number in the path, it can reject the advertisement. AS_PATH length can also influence BGP path selection, with shorter paths generally preferred when other relevant factors are equal. NEXT_HOP identifies the next-hop address, MED influences certain inbound path decisions, and Local Preference influences outbound path selection within an AS.

Question: 327. Which Junos command is most useful for checking the operational status and brief details of all interfaces?

1. show route
   2. show interfaces terse
   3. show chassis hardware
   4. show system uptime

Correct Answer: 2. show interfaces terse

Explanation:

The show interfaces terse command provides a compact summary of interfaces and their operational and administrative states. It is particularly useful as a quick diagnostic tool for determining whether interfaces are up or down and for viewing protocol-family status. show interfaces provides much more detailed information for individual interfaces, while show route focuses on routing information. show chassis hardware displays hardware inventory and show system uptime provides system uptime information.

Question: 328. Which OSPF packet is primarily used to request specific LSAs that a router needs to complete database synchronization?

1. Hello
   2. Link-State Acknowledgment
   3. Database Description
   4. Link-State Request

Correct Answer: 4. Link-State Request

Explanation:

An OSPF Link-State Request (LSR) packet is used when a router needs specific LSAs from a neighboring router during database synchronization. After comparing database information, a router can send an LSR for missing or newer LSAs. The neighbor responds with a Link-State Update containing the requested LSAs. Hello packets establish and maintain neighbor relationships, Database Description packets summarize database contents, and Link-State Acknowledgments confirm receipt of LSAs.

Question: 329. Which IPv6 address is the loopback address?

1. FE80::1
   2. FF02::1
   3. ::1
   4. 2001:db8::1

Correct Answer: 3. ::1

Explanation:

The IPv6 loopback address is ::1. It serves the same general purpose as the IPv4 loopback address 127.0.0.1, allowing a device to send traffic to itself for local testing and communication. FE80::/10 is the IPv6 link-local range, while FF00::/8 is reserved for multicast addresses. 2001:db8::/32 is reserved for documentation and examples. The loopback address is represented by a 128-bit address with all bits set to zero except the final bit.

Question: 330. Which BGP community is designed to prevent a route from being advertised outside the local autonomous system?

1. no-advertise
   2. internet
   3. no-export
   4. local-AS

Correct Answer: 3. no-export

Explanation:

The BGP no-export community tells a BGP speaker that a route should not be advertised outside the local autonomous system, subject to the applicable BGP environment and policy. It is useful when a route should be shared within an AS but should not be propagated to external autonomous systems. no-advertise has a stricter scope because it prevents advertisement to any BGP peer. The internet community generally indicates that the route can be advertised to other BGP peers according to policy.

Question: 331. Which Junos command displays the forwarding table used to determine the next-hop forwarding behavior for packets?

1. show route forwarding-table
   2. show configuration
   3. show ospf database
   4. show bgp summary

Correct Answer: 1. show route forwarding-table

Explanation:

The show route forwarding-table command displays information from the forwarding table used to make packet-forwarding decisions. The routing table contains control-plane route information, while the forwarding table represents the information used by the forwarding plane to determine where packets should be sent. This distinction is important during troubleshooting because a route can exist in the routing table while forwarding behavior may depend on how that route has been installed into the forwarding table.

Question: 332. Which OSPF state indicates that two routers have established bidirectional communication but have not necessarily formed a full adjacency?

1. Down
   2. Full
   3. 2-Way
   4. Loading

Correct Answer: 3. 2-Way

Explanation:

The OSPF 2-Way state indicates that two routers have successfully established bidirectional communication. On some network types, such as broadcast multiaccess networks, not every neighboring router necessarily proceeds to Full adjacency. Instead, routers may remain in 2-Way with non-DR and non-BDR neighbors while forming full adjacencies with the DR and BDR. The Full state indicates synchronized link-state databases, while Down means no valid Hello relationship has been established and Loading occurs later during database synchronization.

Question: 333. What is the primary purpose of BFD in a Junos network?

1. To advertise BGP communities
   2. To provide rapid detection of forwarding-path failures
   3. To calculate OSPF shortest paths
   4. To aggregate Ethernet interfaces

Correct Answer: 2. To provide rapid detection of forwarding-path failures

Explanation:

Bidirectional Forwarding Detection (BFD) provides rapid detection of failures along a forwarding path. It can operate alongside routing protocols such as OSPF and BGP, allowing those protocols to react more quickly than they might through their normal protocol timers alone. BFD does not calculate routing paths, advertise BGP communities, or combine physical Ethernet interfaces. Its main purpose is fast failure detection, which can help improve convergence in networks where rapid detection is required.

Question: 334. Which OSPF router role connects one OSPF area to another and advertises inter-area routing information?

1. ASBR
   2. DR
   3. BDR
   4. ABR

Correct Answer: 4. ABR

Explanation:

An Area Border Router (ABR) connects multiple OSPF areas and exchanges routing information between those areas. An ABR maintains information about its attached areas and can originate inter-area Summary LSAs to advertise networks from one area into another. A Designated Router and Backup Designated Router are roles used on certain multiaccess network segments. An ASBR, or Autonomous System Boundary Router, connects OSPF to external routing domains by redistributing routes into OSPF. These roles serve different purposes.

Question: 335. Which Junos command checks whether the current candidate configuration can be committed without configuration errors?

1. commit check
   2. show | compare
   3. commit confirmed
   4. rollback 1

Correct Answer: 1. commit check

Explanation:

The Junos commit check command validates the candidate configuration without actually activating it. It is useful for detecting syntax or configuration consistency problems before performing a normal commit. show | compare displays differences between the candidate and active configurations, while commit confirmed activates a configuration with a confirmation timer. rollback 1 loads a previous configuration version into the candidate configuration. Therefore, commit check is specifically associated with pre-commit validation.

Question: 336. Which IPv4 address is a limited broadcast address?

1. 224.0.0.1
   2. 255.255.255.255
   3. 0.0.0.0
   4. 127.255.255.255

Correct Answer: 2. 255.255.255.255

Explanation:

255.255.255.255 is the IPv4 limited broadcast address. It is used to reach all IPv4 hosts on the local network segment and is not forwarded by routers. 224.0.0.1 is an IPv4 multicast address used to identify all hosts on a local subnet, while 0.0.0.0 has several special uses including representing an unspecified address or default route depending on context. The 127.0.0.0/8 range is reserved for loopback traffic.

Question: 337. Which routing protocol uses TCP port 179 for its transport connection?

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

Correct Answer: 3. BGP

Explanation:

BGP uses TCP port 179 to establish reliable transport sessions between BGP peers. TCP provides reliable, ordered delivery, allowing BGP to exchange routing information without implementing its own reliable transport mechanism. OSPF operates directly over IP rather than TCP or UDP, RIP uses UDP port 520 for IPv4, and IS-IS operates directly at the network layer using its own protocol mechanisms. Knowing BGP’s TCP port is useful when troubleshooting firewall filters, security policies, and failed peering sessions.

Question: 338. Which OSPF LSA type is generated by an ABR to advertise networks from one area into another?

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

Correct Answer: 4. Type 3 Summary LSA

Explanation:

Type 3 Summary LSAs are originated by OSPF Area Border Routers to advertise networks from one area into another. They provide inter-area routing information and allow routers in one OSPF area to learn about destinations located in another area. Type 1 Router LSAs describe individual routers within an area, Type 2 Network LSAs describe multiaccess network segments through the DR, and Type 5 AS External LSAs describe external routes redistributed into OSPF. Therefore, Type 3 is the appropriate LSA for inter-area network advertisements.

Question: 339. What does the OSPF dead interval determine?

1. The maximum number of OSPF areas
   2. The time a router waits without receiving expected Hello packets before declaring a neighbor down
   3. The number of LSAs a router can store
   4. The SPF calculation interval

Correct Answer: 2. The time a router waits without receiving expected Hello packets before declaring a neighbor down

Explanation:

The OSPF dead interval defines how long a router can go without receiving valid Hello packets from a neighbor before declaring that neighbor unavailable. The Hello and dead intervals must be compatible between OSPF neighbors for an adjacency to form correctly. When the dead timer expires, the router removes the neighbor relationship and updates its OSPF information accordingly. The dead interval does not determine the number of areas, the number of LSAs that can be stored, or the SPF calculation interval.

Question: 340. Which BGP attribute is generally preferred with a shorter value when comparing otherwise eligible paths?

1. Local Preference
   2. MED
   3. NEXT_HOP
   4. AS_PATH

Correct Answer: 4. AS_PATH

Explanation:

AS_PATH length can influence BGP path selection, with a shorter AS_PATH generally preferred when the relevant earlier path-selection criteria are equal. A shorter path usually represents fewer autonomous-system hops between the local AS and the destination. Local Preference follows the opposite general comparison principle because higher values are preferred. MED is also commonly preferred at a lower value, but its comparison behavior and scope differ from AS_PATH. NEXT_HOP is used to identify the next-hop address rather than being selected based on a shorter or longer value.