Deploying Cisco Service Provider Network Routing (SPROUTE) Free Practice Test — 30 Questions

Question 1

A service provider\'s network operations center (NOC) is tasked with optimizing inbound traffic flow from a large enterprise customer\'s network. The enterprise customer is peering with the service provider at multiple points of presence (PoPs). The service provider wishes to influence the enterprise customer to send traffic destined for the service provider\'s network towards a specific, more capacity-rich ingress PoP, without imposing strict policies on the enterprise\'s edge routers. The service provider has already established BGP peering with the enterprise at these multiple locations. Which BGP path attribute or mechanism, when configured by the service provider on routes advertised *to* the enterprise customer, would most effectively achieve this goal by signaling preference without directly dictating routing policy on the enterprise side?

Accepted Answer

BGP Community attributes

Question 2

A service provider\'s core network recently underwent a significant hardware upgrade across several Points of Presence (PoPs). Following the upgrade, engineers observed intermittent packet loss and widespread BGP route flapping, impacting customer traffic. Initial investigations suggest that BGP neighbor adjacencies are unstable, frequently transitioning between states. Which of the following diagnostic and remediation strategies would most effectively address the observed network instability by focusing on the root cause of BGP operational disruption?

Accepted Answer

Thoroughly review and correct all BGP neighbor configurations, including AS numbers, update-source settings, and applied route-maps, to ensure consistency and proper adjacency establishment across the upgraded infrastructure.

Question 3

A service provider\'s network is experiencing a surge in customer complaints citing intermittent connectivity and sluggish data speeds across a critical MPLS Traffic Engineering (TE) tunnel. Initial provisioning was performed using standard TE policies, but post-deployment observations reveal a persistent inability to maintain consistent performance, particularly during periods of fluctuating link utilization and unexpected routing changes. The network\'s existing mechanisms appear to struggle with real-time adjustments to traffic paths when network conditions deviate from the initial provisioning parameters. Which of the following approaches would most effectively address the underlying issue of performance degradation due to a lack of dynamic path adaptation in this MPLS TE deployment?

Accepted Answer

Implement a policy that leverages real-time network telemetry and dynamically recomputes and re-signals MPLS TE tunnel paths based on current link availability, congestion levels, and explicit path constraints, ensuring continuous optimization.

Question 4

A senior network engineer is tasked with resolving a critical connectivity issue impacting a major financial services client. Customers are reporting intermittent packet loss and elevated latency on traffic routed between two critical data centers. Upon initial investigation, the engineer identifies that a Border Gateway Protocol (BGP) peering session between their Autonomous System (AS) and a peered AS has flap. The engineer first verifies the health and convergence of the underlying Intermediate System to Intermediate System (IS-IS) routing protocol, confirming that all network segments are reachable and that BGP next-hops are properly resolved within the IGP. Subsequently, the engineer examines the BGP configuration on both peering routers, specifically checking neighbor statements, authentication settings, and route advertisement policies. The engineer\'s systematic approach, moving from symptom to protocol verification to configuration analysis, is key to restoring service. Which of the following behavioral competencies best describes the engineer\'s approach to resolving this complex network outage?

Accepted Answer

Demonstrates strong problem-solving abilities through systematic analysis and methodical troubleshooting, coupled with technical knowledge of routing protocols and network fundamentals.

Question 5

Anya, a network engineer for a large telecommunications provider, is troubleshooting a service degradation issue affecting voice and video traffic traversing an MPLS network between two core data centers. Users report intermittent call drops and pixelation, but the underlying MPLS LSPs remain signaled and active. Initial diagnostics on the ingress router reveal that a specific class of service, designated for high-priority voice traffic (mapped to the Expedited Forwarding PHB), is experiencing a high rate of packet drops under peak load conditions. The configured traffic control policy on the ingress interface includes a policing action for this voice class, set to a committed information rate (CIR) of $100$ Mbps with a burst size (Bc) of $1600$ bytes. What is the most direct technical reason for the observed packet loss for the voice traffic in this scenario?

Accepted Answer

The policing action on the ingress interface is configured to drop voice traffic that exceeds the committed information rate of $100$ Mbps, even if the overall link capacity is not saturated.

Question 6

A service provider\'s core network is experiencing a recurring issue where a critical customer\'s IP prefix (e.g., 192.0.2.0/24) is intermittently disappearing from BGP routing tables across various peering points, causing service disruptions. Network engineers have confirmed the BGP sessions themselves are largely stable, but the advertisement of this specific prefix is highly erratic. The team needs to identify the most effective initial diagnostic step to pinpoint the root cause of this prefix instability.

Accepted Answer

Analyze the BGP routing table for the specific customer prefix to identify the events triggering its withdrawal and re-advertisement.

Question 7

Consider a scenario where a Border Gateway Protocol (BGP) router within an Autonomous System (AS) receives two distinct routes for the network prefix 192.168.1.0/24. Both routes are learned from external BGP (eBGP) peers located in different neighboring ASes. Upon inspection, it is confirmed that no explicit `LOCAL_PREF` attribute has been configured or advertised for either of these routes. Given this configuration, what is the primary BGP attribute that the router will evaluate to determine the preferred outbound path after the initial `LOCAL_PREF` comparison results in a tie due to its absence?

Accepted Answer

AS_PATH length

Question 8

A large financial institution reports sporadic, high-impact packet loss on their primary MPLS L3VPN service. The network operations center\'s initial diagnostic sweep, focusing on interface utilization, BGP peer stability, and basic ping tests to customer edge (CE) routers, has not identified a clear cause. The engineering team is tasked with resolving this critical issue, which is affecting inter-branch connectivity for the client. Which behavioral competency is most crucial for the engineering team to demonstrate to effectively pivot their troubleshooting strategy and identify the root cause, moving beyond the initial, insufficient diagnostics?

Accepted Answer

Adaptability and Flexibility, specifically the ability to pivot strategies and systematically analyze complex, ambiguous issues.

Question 9

A service provider\'s core MPLS network is experiencing sporadic packet loss on a primary inter-PE link connecting two critical aggregation points. Standard interface statistics show no excessive utilization or physical errors. The network relies on OSPF as the IGP and LDP for label distribution. The loss is not consistently reproducible and seems to occur during periods of moderate network activity, affecting multiple VPNs traversing this link. Which of the following diagnostic approaches would be the most effective initial step to isolate the root cause of this intermittent packet loss?

Accepted Answer

Examine OSPF adjacency states and LDP neighbor status for any signs of instability or flapping between the affected PE routers and their directly connected neighbors within the OSPF domain.

Question 10

Anya, a senior network engineer at a large Tier-1 service provider, is investigating a persistent issue where a critical customer\'s IP prefix is intermittently flapping in the BGP routing table across multiple edge routers. This instability is causing unpredictable traffic shifts and service degradation. Initial checks reveal no physical layer issues or obvious misconfigurations on the directly connected customer interfaces. The prefix is being advertised by the customer and received by Anya\'s network, and then subsequently re-advertised to other peers. The flapping occurs without a clear pattern related to scheduled maintenance or known network events. What diagnostic strategy would most effectively pinpoint the root cause of this BGP route instability within the provider\'s infrastructure?

Accepted Answer

Analyze the BGP attributes (e.g., Local Preference, AS_PATH, MED, Origin) for the affected prefix as seen by various internal and external BGP peers, and review route dampening configurations applied to this prefix or its originating AS.

Question 11

A critical outage has paralyzed a metropolitan internet exchange point (IXP), rendering services for numerous enterprise clients unavailable. Initial diagnostics point to a failure in BGP route propagation between the IXP\'s edge routers and a major upstream provider. Network engineers have identified that a recent policy change, intended to influence route selection, has inadvertently caused internal BGP (iBGP) sessions to advertise routes with an incorrect next-hop attribute to other internal routers. This misconfiguration is preventing the advertised routes from being installed in the routing tables of downstream iBGP speakers, effectively isolating segments of the network. Considering the immediate need for service restoration and the underlying cause, which of the following actions would most effectively and directly resolve the issue, aligning with standard BGP operational principles and service provider best practices?

Accepted Answer

Remove the `next-hop-self` command from the outbound policy applied to the iBGP peering session that is experiencing the incorrect next-hop advertisement.

Question 12

A service provider\'s core MPLS network is experiencing sporadic packet loss on a critical segment connecting two major data centers. Network engineers have observed that the issue is not consistently reproducible and appears to occur during periods of moderate to high traffic utilization. The network employs OSPF as the IGP and LDP for label distribution. What systematic approach would most effectively diagnose and resolve this intermittent packet loss, considering the potential for control plane instability, forwarding plane anomalies, and physical layer degradation within the MPLS infrastructure?

Accepted Answer

Verify physical interface statistics for errors, examine MPLS forwarding table entries for LSP stability, analyze IGP adjacencies for convergence anomalies, review RSVP-TE signaling (if applicable) for path disruptions, and inspect sampled NetFlow data for traffic patterns indicating congestion or misdirection.

Question 13

A service provider, \"GlobalLink,\" operates multiple peering points with a large international transit provider, \"WorldNet.\" GlobalLink\'s network architecture necessitates directing all inbound traffic from WorldNet destined for GlobalLink\'s customer base within the European region to egress through its Frankfurt peering point, rather than its London or Paris points. This strategic decision is driven by contractual obligations with local content providers and optimized inter-domain routing efficiency. Which BGP attribute manipulation strategy would GlobalLink most effectively employ to influence WorldNet to prefer the Frankfurt ingress point for traffic destined for GlobalLink\'s European customers?

Accepted Answer

Advertise routes to WorldNet through the Frankfurt peering link with a lower MED value than routes advertised through London and Paris.

Question 14

A service provider network engineer is investigating reports of degraded Voice over IP (VoIP) services and intermittent application timeouts on a critical MPLS traffic engineered path between core routers R1 and R3, with R2 as an intermediate hop. Initial diagnostics confirm that physical layer issues are not present, and basic IP reachability is stable. The network has been observed to exhibit instability during periods of dynamic re-evaluation of Interior Gateway Protocol (IGP) metrics. Which of the following control plane behaviors is most likely the root cause of this intermittent packet loss on the traffic engineered path?

Accepted Answer

Frequent RSVP-TE LSP re-signaling triggered by dynamic IGP metric recalculations leading to temporary path disruptions.

Question 15

During a routine network audit, it\'s observed that a critical customer prefix is experiencing significant BGP route flapping, leading to intermittent connectivity and increased CPU utilization on edge routers. The network engineering team needs to implement a strategy that addresses this instability without broadly suppressing potentially valid routes or overly complicating the existing BGP configuration. Which of the following approaches most effectively balances stability, operational simplicity, and the ability to manage specific prefix behavior in a dynamic service provider environment?

Accepted Answer

Utilize a route-map to specifically match the customer's prefix and influence its BGP update processing behavior, allowing for granular control over the prefix's stability.

Question 16

Anya, a senior network engineer for a large telecommunications provider, is tasked with resolving intermittent packet loss affecting premium voice and video traffic traversing a critical MPLS backbone segment. The issue is not consistently reproducible and appears correlated with specific traffic flows utilizing DiffServ markings and MPLS EXP bits. Initial troubleshooting confirmed physical layer integrity and basic MPLS forwarding path correctness. Anya suspects that transient buffer exhaustion on intermediate Label Switching Routers (LSRs), possibly exacerbated by the interaction of specific DSCP values and MPLS EXP bit settings in queuing mechanisms, is the root cause. She needs to implement a solution that minimizes service impact while effectively diagnosing and resolving the problem. Which of the following approaches best demonstrates adaptability and effective problem-solving under pressure in this scenario?

Accepted Answer

Implement granular traffic analysis using NetFlow and telemetry data to identify specific DSCP/MPLS EXP combinations correlated with packet loss, followed by targeted adjustments to queuing parameters on affected LSRs to mitigate head-of-line blocking.

Question 17

A service provider\'s core network is experiencing intermittent flapping of a specific /24 IPv4 prefix advertisement to a key peering partner. The BGP session with this partner remains stable, and initial checks reveal no obvious configuration syntax errors on the local BGP configuration for the affected prefix. This issue arose shortly after the implementation of a new traffic engineering policy designed to optimize path selection by manipulating BGP attributes, specifically adjusting the Multi-Exit Discriminator (MED) for inbound routes from this partner and influencing outbound advertisements based on perceived link quality metrics via local preference. Which of the following is the most probable underlying cause for this observed behavior?

Accepted Answer

An unintended consequence of the recently implemented traffic engineering policy, causing the BGP speaker to repeatedly re-evaluate and withdraw/re-advertise the prefix due to subtle attribute interactions or policy misapplication.

Question 18

Anya, a network engineer for a global financial services firm, is troubleshooting intermittent connectivity issues impacting their primary data aggregation service, which requires low latency and high bandwidth as mandated by financial regulatory bodies. The firm utilizes a multi-homed BGP network with two upstream Internet Service Providers (ISPs): ISP-X and ISP-Y. The firm\'s internal policy dictates that traffic destined for its critical financial data service should preferentially egress through ISP-X, which offers superior performance characteristics. However, analysis of traffic flow indicates that a significant portion of inbound traffic for this service is still being routed via ISP-Y, leading to occasional performance degradation. Anya needs to implement a BGP configuration change to ensure that ISP-X directs more inbound traffic for the financial data service prefix to the firm\'s network.

What BGP configuration adjustment should Anya prioritize to influence ISP-X to prefer the firm\'s network paths advertised via ISP-X for inbound traffic to the financial data service?

Accepted Answer

Configure a lower Multi-Exit Discriminator (MED) value on the advertisements of the financial data service prefix sent to ISP-X.

Question 19

A service provider operates a network with two distinct peering points to an external Autonomous System (AS) for Internet connectivity. One peering is established over a private MPLS backbone, and the other is a direct Ethernet circuit. The network engineering team has observed suboptimal outbound traffic engineering, with traffic occasionally utilizing the direct Ethernet link when the MPLS backbone would offer superior performance characteristics and predictable latency. The goal is to influence BGP to preferentially select the MPLS path for all outbound traffic destined for this external AS, without altering any other routing policies or AS path attributes.

Which BGP attribute manipulation would most effectively achieve this objective and why?

Accepted Answer

Increase the 'Local Preference' attribute for routes learned via the MPLS backbone peering session.

Question 20

A large Tier-1 service provider is grappling with persistent, yet sporadic, Border Gateway Protocol (BGP) route instability for a critical enterprise customer\'s IP prefix. Network operations center (NOC) engineers report a pattern of rapid advertisement and withdrawal, impacting service continuity. However, the current diagnostic framework relies heavily on manual log correlation across various network devices and limited visibility into the underlying causes, leading to prolonged resolution times and a reactive posture. This situation impedes the provider\'s ability to guarantee service level agreements (SLAs) and maintain customer confidence. Which core behavioral competency, when enhanced, would most effectively equip the network engineering team to proactively identify, analyze, and permanently resolve such complex, intermittent routing anomalies, thereby improving overall network stability and operational efficiency?

Accepted Answer

Problem-Solving Abilities

Question 21

A large telecommunications provider is experiencing intermittent network performance degradations, characterized by packet loss and elevated latency, on a critical MPLS backbone segment linking two major data centers. Initial investigations reveal a correlation between these incidents and periods of high traffic volume originating from a specific customer aggregation point that serves a diverse set of enterprise VPN clients. The core routers are configured for RSVP-TE to facilitate traffic engineering, while BGP is used for VPN route distribution. Network architects suspect that the existing RSVP-TE LSP setup may not be adequately handling the simultaneous signaling and resource reservation requirements for multiple, potentially competing, VPN traffic streams originating from this single customer aggregation point, especially during peak demand.

Which strategic adjustment to the network\'s traffic engineering framework would most effectively address the observed performance anomalies by improving resource utilization and ensuring predictable service delivery for all VPNs?

Accepted Answer

Optimizing RSVP-TE LSP selection algorithms to prioritize bandwidth reservation for critical VPN traffic based on pre-defined QoS policies.

Question 22

Anya, a senior network engineer, is overseeing a critical upgrade of the BGP peering configuration across a large service provider’s backbone. Midway through the planned maintenance window, an unexpected and persistent routing flap is observed on a key transit link, impacting multiple customer prefixes. The original deployment script is no longer applicable due to this emergent behavior, and the root cause is not immediately apparent. Which of the following actions best demonstrates Anya\'s adaptability and flexibility in this high-pressure scenario?

Accepted Answer

Rapidly re-evaluating the current network state and implementing a contingency routing policy to restore service while simultaneously initiating a deep-dive root cause analysis.

Question 23

Anya, a senior network engineer at a major telecommunications provider, is alerted to a significant degradation in service quality for several enterprise clients, manifesting as sporadic packet loss and elevated latency on critical data paths. Initial diagnostics point towards instability within the inter-domain routing fabric. Upon closer examination of BGP neighbor states and route advertisements, Anya observes a pattern of rapid, repeated changes in the reachability of a specific prefix originating from an external peering partner. This instability is propagating across the network, impacting multiple downstream customer connections. Anya needs to implement an immediate mitigation strategy that balances service continuity with the need to investigate the root cause of the route flapping. Which of the following actions represents the most prudent and effective initial response to stabilize the network while allowing for further analysis?

Accepted Answer

Implement BGP dampening for the unstable prefix to suppress its frequent state changes.

Question 24

Anya, a network engineer for a large telecommunications provider, is troubleshooting an intermittent packet loss issue on a critical MPLS backbone link between two major Points of Presence (PoPs). She observes that the packet loss escalates during periods of high network activity and seems to correlate with specific BGP neighbor sessions experiencing frequent route flaps. The underlying cause appears to be rapid changes in the BGP routing table, leading to associated churn in the MPLS Label Information Base (LIB) and potentially label switching conflicts on the affected link. Which of the following actions would be the most effective in stabilizing the network and reducing the observed packet loss by addressing the root cause of the control plane instability impacting the data plane?

Accepted Answer

Implement BGP dampening on the routes exhibiting frequent state changes.

Question 25

Consider a scenario where \"GlobalConnect,\" a major transit provider for a large Internet Service Provider (ISP), announces a unilateral shift from its long-standing settlement-free peering policy to a paid transit model for all traffic originating from or destined for specific large content networks. This change significantly alters the cost-effectiveness of routes previously obtained through this peering. Which of the following actions would best demonstrate the ISP\'s adaptability and strategic problem-solving in response to this disruption, aiming to optimize routing efficiency and minimize operational expenses while maintaining broad network reach?

Accepted Answer

Proactively establish new settlement-free peering agreements with alternative Tier-1 and Tier-2 networks, while simultaneously implementing BGP AS-PATH prepending on routes learned from GlobalConnect that are now subject to transit fees, to de-emphasize these paths for inbound traffic.

Question 26

A network operations team is onboarding a new Tier-1 Internet Service Provider (ISP) peering partner. Shortly after establishing the BGP session, the network begins experiencing intermittent connectivity issues as prefixes from this new peer are frequently suppressed due to route flap damping. The network administrator observes that the new peer\'s routing advertisements are highly dynamic, with prefixes appearing and disappearing rapidly during the initial convergence phase. The team\'s primary objective is to ensure the stability of the overall service provider network while allowing the new peering relationship to stabilize without disrupting existing services. Which adjustment to the BGP route flap damping configuration would best address this situation by allowing for initial instability from the new peer without prematurely suppressing valid routes?

Accepted Answer

Increase the suppress-limit and reuse-limit values for BGP prefixes.

Question 27

A service provider network engineer is investigating a recurring issue where a specific customer\'s IP prefix is intermittently withdrawn and then re-advertised by multiple BGP peers within the provider\'s autonomous system. Initial observations indicate that the flapping is not directly correlated with external network events but appears to be influenced by changes in the provider\'s internal routing policies or the customer\'s own network behavior. The engineer systematically reviews BGP neighbor states, analyzes attribute changes associated with the prefix\'s re-advertisement, and scrutinizes inbound and outbound routing policies applied to the customer\'s connection. This methodical approach, aimed at identifying the underlying cause and developing a stable resolution, best exemplifies which critical behavioral competency in a service provider context?

Accepted Answer

Problem-Solving Abilities, specifically systematic issue analysis and root cause identification.

Question 28

Consider a multinational service provider operating a backbone network with major Points of Presence (PoPs) on the West Coast, East Coast, and in the South. The network engineering team has identified a need to optimize outbound traffic flow, specifically directing a significant portion of customer traffic destined for external networks that is currently transiting through the West Coast PoP to instead egress via the East Coast PoP. This strategic shift aims to leverage better peering agreements and reduce latency for a substantial segment of their customer base. The network utilizes BGP extensively for inter-domain routing. Which BGP attribute manipulation strategy would be most effective in achieving this specific outbound traffic engineering goal, assuming all other BGP attributes are equal or not intentionally manipulated to contradict this objective?

Accepted Answer

Increase the LOCAL_PREF attribute for routes advertised to the East Coast PoP neighbor, while keeping the LOCAL_PREF attribute lower for routes advertised to the South PoP neighbor.

Question 29

Anya, a senior network engineer at a Tier-1 ISP, is troubleshooting a recurring issue where a specific customer prefix, $192.0.2.0/24$, is exhibiting route flapping within the provider\'s network. The customer reports intermittent connectivity. Initial checks reveal that the prefix is being advertised by multiple eBGP peers. Anya suspects that a change in an external network\'s advertisement is causing the BGP best path selection to oscillate. She needs to identify the most probable cause for this instability to guide her further investigation. Which BGP attribute, when inconsistently advertised or received, is most likely to induce such route flapping in this scenario?

Accepted Answer

Multi-Exit Discriminator (MED)

Question 30

A service provider\'s core network, employing MPLS and BGP for inter-AS routing, is experiencing intermittent packet loss and elevated latency on a critical link between two core routers, R1 and R2. This degradation began shortly after the activation of a new, high-bandwidth VPN service, which has significantly increased traffic volume. The engineering team has observed that the issue is transient, correlating with periods of high traffic on the new VPN, and appears to stem from routing protocol behavior rather than physical link failure. Which of the following adjustments to BGP policy would be most effective in mitigating these symptoms by influencing path selection to accommodate the new service\'s demands?

Accepted Answer

Incrementally increase the Local Preference attribute for routes associated with the new VPN service to steer traffic towards more stable internal paths.

Deploying Cisco Service Provider Network Routing (SPROUTE) Free Practice Test — 30 Questions

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