Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 1 / 8 Exam : JN0-364 Title : https://www.passcert.com/JN0-364.html Service Provider Routing and Switching - Specialist (JNCIS-SP) Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 2 / 8 1.You must ensure that your routing platform with redundant REs continues to forward packets, even if one RE fails. Which technology would you use to accomplish this task? A. NSB B. LAG C. BFD D. GRES Answer: D Explanation: For Juniper platforms equipped with dual Routing Engines (REs), the fundamental technology required to provide high availability during a hardware or software failure of the primary RE is Graceful Routing Engine Switchover (GRES). According to Juniper Networks technical documentation, GRES allows the backup RE to stay in a "hot" standby state. When GRES is enabled, the primary RE synchronizes critical state information with the backup RE, specifically the chassis state and the interface state. This synchronization includes the Packet Forwarding Engine (PFE) configuration. When the primary RE fails, the backup RE takes over immediately. Because the PFE (which resides on the line cards) was already synchronized and is not restarted during the switchover, the router continues to forward packets that are already in flight or part of established flows. This prevents a complete network outage during an RE failover. Comparison with other options: NSB (Non-Stop Bridging - Option A): Focuses specifically on maintaining Layer 2 protocol states (like STP) during a switchover. LAG (Link Aggregation - Option B): Provides redundancy for physical links, not the control plane or the RE. BFD (Bidirectional Forwarding Detection - Option C): Is a protocol used for rapid detection of link or neighbor failures; it does not protect the RE or maintain forwarding during an internal switchover. It is important to note that while GRES maintains the forwarding state, it does not by itself maintain the routing protocol state (adjacencies). To keep OSPF or BGP sessions from dropping during the switchover, GRES must be paired with Non-Stop Active Routing (NSR). However, as the question focuses on the core requirement of continuing to forward packets, GRES is the foundational technology. 2.Which two statements regarding GRE and IP-IP tunnels are correct? (Choose two.) A. These tunnels add additional overhead to the packets that traverse them. B. These tunnels do not add any overhead to the packets that traverse them. C. These tunnels offer secure encryption mechanisms. D. These tunnels do not offer encryption mechanisms. Answer: A D Explanation: In Juniper Networks Junos OS, Generic Routing Encapsulation (GRE) and IP-in-IP (IP-IP) are common tunneling mechanisms used to transport packets across a network by encapsulating them within another protocol. Understanding the header structure and the limitations of these protocols is essential for proper MTU (Maximum Transmission Unit) management and security design. Overhead (Option A): Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 3 / 8 Both GRE and IP-IP tunnels operate by adding an additional IP header to the original packet. An IP-IP tunnel (Protocol 4) adds a20-byteIPv4 header. A GRE tunnel (Protocol 47) adds the same20-bytedelivery IP header plus a minimum4-byteGRE header (totaling 24 bytes, which can increase if keys or sequencing are used). Because these headers are added to the payload, the total size of the packet increases. This "overhead" means that if the original packet was already at the MTU limit (e.g., 1500 bytes), the encapsulated packet will exceed it, potentially leading to fragmentation or the need to adjust the TCP MSS (Maximum Segment Size). Encryption (Option D): Crucially, according to Juniper Service Provider documentation, neither GRE nor IP-IP provides native encryption or data confidentiality. They are encapsulation protocols, not security protocols. The payload remains in cleartext and is visible to any device along the path. If security and encryption are required for data traversing these tunnels, they must be combined with IPsec (IP Security). While GRE is often used as the "carrier" for IPsec (to allow multicast or dynamic routing protocols which IPsec alone does not support), the GRE protocol itself remains an unencrypted delivery mechanism. Therefore, statements A and D accurately describe the architectural behavior of these tunnel types. 3.For two or more switches to participate in the same MSTP region, which parameter must match? A. Region name B. Extended system ID C. Root bridge priority D. Root bridge ID Answer: A Explanation: Multiple Spanning Tree Protocol (MSTP), as defined in IEEE 802.1s and implemented in Juniper Networks Junos OS, allows for the grouping of VLANs into specific spanning tree instances. This provides significant scalability and load-balancing advantages over traditional STP or RSTP. To achieve this, switches must be grouped into logical "Regions." According to Juniper documentation, for two or more switches to be considered part of the same MSTP Region, they must possess an identical MSTP Configuration Identifier. This identifier consists of three specific attributes that must match exactly across all participating switches: MSTI Name (Region Name): A descriptive string (up to 32 characters) that identifies the region. MSTI Revision Level: A numerical value (0 – 65535) used to track configuration changes. VLAN-to-Instance Mapping: The specific table that defines which VLAN IDs are associated with which Multiple Spanning Tree Instances (MSTIs). If even one of these parameters — such as the Region name (Option A) — differs, the switches will treat each other as being in separate regions. When switches are in different regions, they interact using the Common Spanning Tree (CST), effectively seeing the other region as a single "virtual bridge, " which limits the granularity of traffic engineering. The Extended system ID (Option B) is a component of the Bridge ID used to carry VLAN information in PVST+ but is not a region-matching requirement. Root bridge priority (Option C) and Root bridge ID (Option D) are variables used during the STP election process to determine the topology's root, but they do not define the boundaries of an MSTP region itself. Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 4 / 8 4.You are monitoring OSPF on a router and notice frequent state changes between Full and Down. Which condition would cause this behavior? A. physical interface flapping B. route preference mismatch C. area ID mismatch D. MTU mismatch Answer: A Explanation: When troubleshooting OSPF in a service provider environment, distinguishing between "stuck" adjacencies and "flapping" adjacencies is the first step. A session that transitions frequently between Full and Down indicates that the relationship can be established successfully (meaning parameters match), but it cannot be maintained. According to Juniper Networks documentation, the most common cause for a session to drop from Full to Down is the expiration of the Dead Interval. If a router does not receive a Hello packet within the Dead Interval (usually 40 seconds), it tears down the adjacency. A physical interface flapping (Option A) is the primary trigger for this. If the physical link or the underlying transport (like a leased line or a microwave link) goes down even momentarily, the OSPF process immediately detects the interface failure, flushes the neighbors, and moves the state to Down. As soon as the interface comes back up, the routers perform the Hello exchange and reach the Full state again, creating the flapping cycle. Analysis of other options: MTU Mismatch (Option D): This typically causes the adjacency to get "stuck" in the Exchange or ExStart state. The routers can exchange small Hello packets, but when they try to send larger Database Description (DBD) packets that exceed the MTU, the packets are dropped, preventing the session from ever reaching "Full." Area ID Mismatch (Option C): This prevents the adjacency from even reaching the Init state; the routers will never form a neighbor relationship. Route Preference (Option B): This affects which route is chosen for the forwarding table but has no impact on the OSPF neighbor state machine itself. 5.Which feature allows Junos OS to perform recursive lookups for static route next hops? A. resolve B. discard C. reject D. next-table Answer: A Explanation: In standard routing, astatic route is typically considered valid only if the specified next-hop IP address is directly reachable on a local subnet. However, in complex service provider designs, the next-hop might be a "distant" IP address that is reachable through another route (such as a BGP route or another static route). This process of looking up a next-hop within another routing entry is called recursive lookup. In Junos OS, the resolve (Option A) parameter is explicitly used to enable this behavior for static routes. According to Juniper technical documentation, when you append the resolve keyword to a static route configuration, you are instructing the Routing Engine to search the routing table to find a path to that distant next-hop. Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 5 / 8 For example: set routing-options static route 10.1.1.0/24 next-hop 192.168.100.1 resolve If 192.168.100.1 is not on a local interface but is reachable via an OSPF route, the router will "resolve" the path and install the 10.1.1.0/24 route into the forwarding table using the OSPF path's exit interface. Why other options are incorrect: Discard (Option B) and Reject (Option C) are "next-hop types" used to drop traffic, either silently (discard) or by sending an ICMP unreachable message (reject). Next-table (Option D) is used for Inter-VRF routing, where the router is told to look up the destination in a completely different routing instance (like a VRF table), which is a different architectural function than a recursive next-hop lookup within the same table. 6.Exhibit: user@Router-1> show route 172.24/16 inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden) + = Active Route, - = Last Active, * = Both ... 172.24.0.0/24 *[OSPF/150] 01: 31: 31, metric 0, tag 0 > to 172.20.0.2 via ge-0/0/2.0 to 172.20.1.2 via ge-0/0/3.0 user@Router-1> show route forwarding-table Routing table: default.inet Internet: Destination Type RtRef Next hop Type Index NhRef Netif ... 172.24.0.0/24 user 0 172.20.0.2 ucst 551 2 ge-0/0/2.0 172.20.1.2 ucst 552 2 ge-0/0/3.0 Referring to the exhibit, which two statements are true? (Choose two.) A. The router is performing default route load-balancing behavior. B. The default route load-balancing behavior of this router has been modified. C. This router will only choose the next hop with a > next to it in the routing table. D. This router will choose both next hops in the routing table. Answer: B D Explanation: In Junos OS, understanding the distinction between the Routing Information Base (RIB) and the Forwarding Information Base (FIB) is fundamental to analyzing traffic patterns and load-balancing behavior. The RIB (show route) contains all prefixes learned via various protocols, while the FIB (show route forwarding-table) contains only the active next-hops that are actually programmed into the Packet Forwarding Engine (PFE). According to Juniper Networks technical documentation, the default behavior for Junos OS when encountering Equal-Cost Multipath (ECMP) routes is to select only a single next-hop from the available candidates in the RIB and install that single path into the FIB. In a default state, even if the show route output displays multiple next-hops for a destination like 172.24.0.0/24, only one would have the active route symbol ( >) and only that one would appear in the forwarding table. In the provided exhibit, the show route output shows two next-hops for 172.24.0.0/24, but only the first Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 6 / 8 one (172.20.0.2) is marked with the>symbol as the active selection. However, the subsequent show route forwarding-table output reveals that both next-hops (172.20.0.2 and 172.20.1.2) are currently present in the forwarding table for that same destination. This discrepancy indicates that the default load-balancing behavior has been modified (Option B). This modification is typically achieved by creating a routing policy with the action then load-balance per-packet (which actually results in flow-based load balancing) and applying it to the forwarding table via the export statement under [edit routing-options forwarding-table]. Because the forwarding table now contains both next-hops, the router is no longer restricted to a single path. Therefore, the router will choose both next-hops in the routing table (Option D) for packet forwarding, distributing flows across the two available Gigabit Ethernet interfaces (ge-0/0/2.0 and ge-0/0/3.0). This ensures higher utilized bandwidth and provides redundancy at the data plane level. 7.You are the administrator for two Junos routers called R1 and R2. These two routers are directly connected to each other. These two routers run IS-IS and BFD. R1 is configured to send BFD packets every 300 milliseconds. R2 is configured to send BFD packets every 400 milliseconds. In this situation, what is the expected outcome? A. Each router will send BFD packets at the rate that has been locally configured. B. BFD will fail due to the mismatched timers. C. Each router will negotiate to send BFD packets at the slowest of the two rates. D. Each router will negotiate to send BFD packets at the fastest of the two rates. Answer: C Explanation: In the context of Juniper Networks High Availability, Bidirectional Forwarding Detection (BFD) is a lightweight protocol designed to provide fast failure detection for the forwarding path. Unlike the slow "hello" mechanisms found in IGPs like OSPF or IS-IS, BFD can detect link or neighbor failures in sub-second intervals. According to Juniper Networks technical documentation, BFD operates through a negotiation process. When two routers establish a BFD session, they exchange their locally configured Minimum Transmit Interval and Minimum Receive Interval within the BFD control packets. The fundamental rule of BFD negotiation is that the routers must agree on a common timing value that accommodates the slower of the two devices to ensure stability and prevent "false positives" (detecting a failure when none exists simply because one router cannot keep up with the processing speed). In this scenario, R1 expects to send at 300ms, while R2 is configured for 400ms. During the handshake, R1 informs R2 it is capable of 300ms, but R2 informs R1 it can only support a minimum of 400ms. Consequently, the routers will negotiate to use the slowest of the two rates (400ms). Specifically, the transmission interval of one router is matched to the receive interval of the other. By choosing the highest common denominator (the slowest rate), the BFD session ensures that both routers have sufficient time to process incoming control packets. This negotiation allows BFD to be highly flexible in heterogeneous environments where different hardware platforms may have varying CPU capabilities for handling rapid heartbeat packets. 8.How are routing loops prevented in internal BGP networks? A. Internal BGP routes are never readvertised to other internal BGP neighbors. B. External BGP routes are never readvertised to other external BGP neighbors. C. External BGP routes are never readvertised to other internal BGP neighbors. Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 7 / 8 D. Internal BGP routes are never readvertised to other external BGP neighbors. Answer: A Explanation: The prevention of routing loops within an Autonomous System (AS) is handled differently than loop prevention between ASes. While External BGP (EBGP) uses the AS_PATH attribute to detect loops, Internal BGP (IBGP) does not modify the AS_PATH. Therefore, a different mechanism is required to ensure that a route does not circulate infinitely inside the network. This mechanism is known as the IBGP Split Horizon rule. According to Juniper Networks documentation and the BGP standard (RFC 4271), a BGP speaker must not advertise a route learned via an IBGP peer to any other IBGP peer. In simpler terms, "what is learned internally, stays local." This rule ensures that a route only travels one "hop" inside the AS — from the router that learned it from an external source to all other internal routers. Because of this rule, IBGP routers do not naturally propagate routes through each other. This creates a requirement for a full mesh of IBGP sessions, where every BGP-speaking router in the AS must have a direct peering session with every other BGP-speaking router. To mitigate the scaling issues of a full mesh in large service provider networks, architects use Route Reflectors or Confederations, which are authorized exceptions to the Split Horizon rule. Option B is incorrect because EBGP peers do advertise EBGP routes to other EBGP peers (this is how the internet works). Option C is incorrect because EBGP-learned routes must be sent to IBGP peers so the internal network knows how to reach the outside world. Option D is incorrect because internal routes must be sent to external peers to advertise your network to the internet. 9.What is the default route preference for an aggregate route? A. 180 B. 150 C. 130 D. 5 Answer: C Explanation: In the Junos OS architecture, route preference (often referred to as administrative distance in other vendor platforms) is the primary metric used by the Routing Engine to select the "best" path when multiple protocols provide a route to the same destination. Each routing protocol and route type is assigned a default numeric value; the lower the value, the more preferred the route. According to Juniper Networks technical documentation, an aggregate route is assigned a default preference of 130. Aggregate routes are a form of static-like route used to group specific routes into a single, broader prefix to reduce the size of routing tables and limit the scope of routing updates. They are "protocol-independent" because they are not learned from a dynamic neighbor but are manually defined by the administrator. To understand where130fits in the hierarchy, it is helpful to compare it with other common Junos preferences: Directly connected interfaces: 0 Static routes: 5 Download Valid JNCIS-SP JN0-364 PDF Dumps for Best Preparation 8 / 8 OSPF Internal: 10 IS-IS Level 1/2: 15/18 Aggregate routes: 130 OSPF AS External: 150 BGP (Internal and External): 170 Generated routes: 150 By setting the aggregate route preference to 130, Junos ensures that specific routes learned via IGPs (like OSPF or IS-IS) are preferred over the aggregate. This is essential because an aggregate route is often used as a "catch-all" or a discard route when more specific path information is missing. If the aggregate had a lower preference (like 5), it might override dynamic routing information, leading to suboptimal routing or black-holed traffic. 10.What are two types of BGP messages exchanged while in the Established state? (Choose two.) A. open B. request C. update D. notification Answer: C D Explanation: In the Border Gateway Protocol (BGP) finite state machine (FSM), the Established state is the final and functional stage of a BGP peering session. According to Juniper Networks technical documentation, once a session reaches this state, the two peers have successfully exchanged Open messages and agreed upon session parameters (such as AS numbers, hold timers, and BGP identifiers). Only after the session is "Established" can the routers begin the actual exchange of network layer reachability information (NLRI). The most frequent message type exchanged in the Established state is the UPDATE message. These messages are the heart of BGP operations; they are used to advertise new feasible routes to a peer or to withdraw routes that are no longer reachable. An UPDATE message contains path attributes (like AS-Path, Next-Hop, and Local Preference) and the associated prefixes. In a stable network, UPDATE messages are only sent when there is a change in the topology, adhering to BGP ’ s incremental update philosophy. The second message type that can be exchanged in this state is the NOTIFICATION message. While ideally, a session stays established, any detected error — such as a hold timer expiration, a malformed update, or a manual "clear" command — will trigger the transmission of a NOTIFICATION message. This message informs the peer of the specific error code and immediately causes the BGP session to transition back to the Idle state, tearing down the TCP connection. It is important to note that OPEN messages (Option A) are only used during the session initialization phase to transition from the Open Confirm state to Established. REQUEST (Option B) is not a valid BGP message type defined in the standard (RFC 4271) ; the closest equivalent in functionality would be a Route-Refresh message, which is a separate extension. Therefore, in the context of standard BGP operations within the Established state, Updates and Notifications are the correct answers.