Cisco 300-510 Exam Dumps & Practice Test Questions

Question 1:

After applying the shown configurations to routers R1 and R2, the two devices fail to establish an OSPF neighbor relationship. What is the most probable cause of this failure?

A. The routers fail to authenticate each other.
B. Both routers are configured with the same area ID.
C. The routers share the same network ID.
D. The routers have mismatched IS-types (OSPF router types).

Correct Answer: D

Explanation:

In OSPF (Open Shortest Path First) routing, forming a neighbor relationship between routers depends on several parameters matching correctly. One critical aspect is the router type, also known as IS-type (Intermediate System type), which categorizes routers into roles like Internal Router (IR), Area Border Router (ABR), or Backbone Router (BR). For OSPF routers to successfully establish neighbor adjacencies, their IS-types must be compatible or match depending on the network topology.

Let’s review the options carefully:

• Option A: Authentication mismatches can indeed prevent neighbor formation. If authentication keys or methods differ, routers will reject each other. However, the exhibit does not mention authentication errors, so this is unlikely here.

• Option B: Having the same area ID is generally required for neighbors to form within that area. So, identical area IDs are not a problem; instead, they are necessary.

• Option C: The network ID typically identifies the subnet connecting routers. Sharing the same network ID is normal for routers on the same segment, and it should not prevent neighbor relationships.

• Option D: If routers have different IS-types—say, one is an ABR and the other a standard router—this mismatch can cause neighbor adjacency failure. OSPF uses IS-type to understand the role and scope of routers, and inconsistent types can prevent the formation of neighbor relationships.

Thus, the likely cause in this scenario is that the two routers have different IS-types, which leads to their inability to establish OSPF neighbor adjacencies. Ensuring consistent IS-types is essential for successful OSPF neighbor formation.

Question 2:

Given the configuration shown, what is the correct interpretation of the keepalive and hold timer settings applied?

A. Keepalive interval is 30 seconds; hold timer is 240 seconds.
B. Keepalive interval is 30 milliseconds; hold timer is 240 milliseconds.
C. Hold timer is 30 milliseconds; keepalive interval is 240 milliseconds.
D. Hold timer is 30 seconds; keepalive interval is 240 seconds.

Correct Answer: A

Explanation:

Keepalive and hold timers are crucial components in many network protocols such as OSPF and BGP, helping maintain stable and reliable connections between devices.

• The keepalive timer controls how often a device sends a "heartbeat" message (or hello packet) to its peer to indicate the connection is active. If these messages stop arriving, the connection may be considered down.

• The hold timer defines the amount of time a device will wait without receiving any keepalive messages before declaring the connection as failed.

Typically, the keepalive timer is shorter than the hold timer, allowing multiple keepalive messages to be missed before considering the neighbor unreachable. This approach provides fault tolerance against temporary network delays or drops.

Reviewing the options:

• Option A reflects common practice, with a 30-second keepalive interval and a 240-second hold timer. This means the router sends keepalive messages every 30 seconds and waits up to 240 seconds without hearing from its peer before declaring the connection lost.

• Option B and C incorrectly use milliseconds for both timers. In real-world network configurations, milliseconds are too brief and impractical for keepalive and hold timers, which generally use seconds.

• Option D reverses the typical relationship by setting the hold timer shorter than the keepalive timer, which is unusual and would likely cause premature disconnections.

Hence, Option A is the correct interpretation because it aligns with standard networking timer configurations, providing appropriate intervals to maintain connection stability.

Question 3:

A network administrator notices that even though an aggregate route is being advertised, the receiving router still receives some of the more specific routes along with the aggregate. 

Which configuration change will ensure that only the aggregate route is advertised now and in the future, even if new networks are added?

A. Use the summary-only keyword with the aggregate command
B. Change the AGGRO policy to drop each specific route instead of suppress-route
C. Apply route filtering on the receiving router
D. Modify the AGGRO policy to remove each specific route instead of suppress-route

Correct answer: A

Explanation:

When dealing with route aggregation, the main objective is to simplify the routing table by combining multiple specific routes into a single summarized route. However, if the more specific routes continue to be advertised alongside the aggregate, it defeats the purpose of aggregation and can cause unnecessary routing complexity.

In this case, the issue arises because the specific subnets under the aggregate are still being advertised. To prevent this, the most straightforward and reliable solution is to configure the aggregate route with the summary-only keyword. This option tells the router to advertise only the summarized route, effectively suppressing all the more specific routes underneath it. This ensures the routing table remains clean and only contains the aggregated route, which is exactly what is needed here.

Let’s examine why the other options fall short:

• Option B (dropping each specific route manually) is less efficient because it requires explicit action for each subnet and needs constant updating as new subnets are added, which is error-prone and cumbersome.

• Option C (filtering on the receiving router) only masks the problem by blocking specific routes after they have been sent, rather than stopping their advertisement at the source. This leads to unnecessary traffic and complexity.

• Option D (removing specific routes in the policy) deletes routes but does not address the problem of what is being advertised in the first place. It is not designed to handle route aggregation suppression effectively.

Therefore, the summary-only keyword on the aggregate command is the best practice, ensuring only the aggregate route is advertised both now and as the network evolves.

Question 4:

A network engineer is receiving the 10.11.11.0/24 route from two different upstream providers on router #XR3. The goal is to configure the router so that traffic prefers the next hop 10.0.0.9 as the primary path whenever it is available. 

Which routing policy adjustment should the engineer implement to enforce this preferred route?

A. Assign a weight of 0 to the prefix from 192.168.0.2
B. Set a lower local preference on the prefix from 192.168.0.2
C. Increase the local preference on the prefix from 192.168.0.1
D. Assign a weight of 100 to the prefix from 192.168.0.1

Correct answer: C

Explanation:

In BGP routing, controlling the preferred path within an Autonomous System (AS) is often achieved by manipulating attributes that influence route selection. In this scenario, the network engineer wants to prioritize the route whose next hop is 10.0.0.9 on router #XR3, preferring it over the other route from a different provider.

Among BGP attributes, local preference is the key tool for influencing outbound traffic decisions inside an AS. A higher local preference value means the route is preferred. Adjusting local preference is effective because it affects routing decisions globally within the AS, ensuring consistent path selection across all routers.

Let’s break down the options:

• Option A involves setting the weight of the route from 192.168.0.2 to zero. While weight is a Cisco-specific attribute influencing local route preference, it only applies to the local router and does not propagate throughout the AS. Thus, it will not enforce the preferred route in a consistent way.

• Option B suggests lowering the local preference of the route from 192.168.0.2. While this can indirectly favor the other route, it’s generally better practice to explicitly increase the local preference on the preferred route rather than lowering it on the alternative.

• Option C correctly recommends increasing the local preference of the route from 192.168.0.1 (which leads to next hop 10.0.0.9). This directly instructs the AS to favor this path whenever it is available.

• Option D involves assigning a weight of 100 to the route from 192.168.0.1. Similar to option A, weight affects only the local router and doesn’t influence the overall path selection in the AS, making it less effective for this purpose.

Thus, setting a higher local preference on the route from 192.168.0.1 ensures that traffic prefers the desired next hop 10.0.0.9 consistently across the network. This method is standard for controlling inbound and outbound traffic preferences in BGP within an AS.

Question 5:

After resolving an OSPF adjacency problem, routers 1, 2, and 3 have successfully established neighbor relationships. 

Considering the network setup shown, which statement correctly describes the routing behavior of router 2?

A. Router 2 receives Type 5 LSAs from router 1 advertising its directly connected networks
B. Router 2 forwards packets to router 3 as the next hop for the 192.168.0.0/24 network
C. Router 2 uses router 1 as the next hop for reaching 192.168.0.0/24
D. Router 2 receives Type 7 LSAs from router 3 about its connected subnets

Correct answer: C

Explanation:

Open Shortest Path First (OSPF) is a link-state routing protocol that enables routers to exchange topology information through Link State Advertisements (LSAs). These LSAs allow each router to construct a comprehensive map of the network and determine the best paths for routing traffic.

In the context of the question, routers 1, 2, and 3 have established OSPF neighbor adjacencies. This means they are sharing LSAs and building routing tables accordingly. The question asks which statement about router 2’s routing behavior is correct, specifically regarding the 192.168.0.0/24 subnet.

Option A is incorrect because Type 5 LSAs are external LSAs used to advertise routes outside the OSPF domain, typically by an Autonomous System Boundary Router (ASBR). Since the question doesn’t mention an ASBR or external routes, this option is unlikely.

Option B is wrong because router 2 will usually select the router advertising the subnet directly as the next hop. If router 1 is directly connected or advertising 192.168.0.0/24, router 2 would use router 1 as the next hop, not router 3.

Option C is correct. Router 2 will use router 1 as the next hop to reach 192.168.0.0/24 because router 1 is the one advertising this subnet within the OSPF domain. This follows OSPF’s behavior of choosing the best path based on cost and adjacency.

Option D is incorrect because Type 7 LSAs are specific to Not-So-Stubby Areas (NSSAs) and typically represent external routes injected into NSSAs. Since no NSSA or ASBR is indicated, router 2 receiving Type 7 LSAs from router 3 is unlikely.

In summary, the proper OSPF operation suggests router 2 uses router 1 as the next hop for the 192.168.0.0/24 network, making option C the accurate choice.

Question 6:

While diagnosing communication issues between two IS-IS routing instances, which of the following is a likely reason for the problem?

A. A single interface cannot be assigned to multiple IS-IS instances simultaneously
B. The two IS-IS instances “ISP” and “ISP2” are separate and cannot exchange routing information
C. Incorrect NSEL configuration is preventing neighbor relationships from forming
D. The “ip router is-is” command was omitted from the interface configuration

Correct answer: A

Explanation:

IS-IS (Intermediate System to Intermediate System) is a link-state routing protocol designed to route IP and other network protocols. It supports multiple instances, allowing different routing domains or administrative segments to coexist on the same physical infrastructure.

When troubleshooting communication issues between two IS-IS instances, one common cause is misconfiguration regarding interface assignments. The key limitation is that a single interface cannot belong to more than one IS-IS instance at the same time. Each IS-IS instance manages its own database and neighbor relationships, so overlapping interface assignments can cause conflicts and prevent proper routing updates.

Option A correctly states this limitation, making it the most plausible explanation for communication failures. If an interface is mistakenly configured in two IS-IS instances, the router will not be able to properly establish neighbor adjacencies or advertise routes, causing disruptions in the routing domain.

Option B is incorrect because IS-IS instances are logically separate routing domains but can be configured to exchange routing information if needed, using proper redistribution and policies. The mere fact they are separate does not inherently prevent communication.

Option C mentions the NSEL value, which is part of IS-IS addressing. While important, NSEL misconfiguration is less likely to be the primary cause of neighbor relationship failures compared to interface assignment problems. NSEL mismatches typically affect service access points rather than base neighbor formation.

Option D relates to enabling IS-IS on interfaces via the “ip router is-is” command. Omitting this command would prevent IS-IS from running on the interface entirely, not just cause issues between instances. It’s an important step but not specific to cross-instance communication problems.

In conclusion, ensuring each interface is assigned to only one IS-IS instance is critical for proper routing operation. Thus, option A correctly identifies a typical root cause of inter-instance communication issues.

Question 7:

What method does SR-TE utilize to guide traffic along specific paths in a network?

A. Shortest path computed by IGP
B. Dynamic rules
C. Path policy
D. Explicit maps

Answer: D

Explanation:

Segment Routing Traffic Engineering (SR-TE) is a powerful technique that allows network operators to direct traffic flows along explicit, predefined paths within a network. Unlike traditional traffic engineering methods that rely heavily on signaling protocols like RSVP (Resource Reservation Protocol), SR-TE simplifies the process by embedding routing instructions directly into the packet headers, enabling fine-grained control without additional signaling overhead.

The main mechanism SR-TE uses to steer traffic is explicit maps (also called SR policies). These explicit maps specify the exact route or sequence of network segments (hops) that packets must follow. Network administrators can define these maps manually or generate them automatically based on network policies or constraints. This approach allows precise control over traffic routing, enabling optimization for factors like bandwidth usage, latency, or avoiding congested links.

Let’s analyze the other options to clarify why they are incorrect:

• A. Shortest path calculated by IGP: Interior Gateway Protocols (IGPs) like OSPF or IS-IS calculate the shortest path based on network topology, but SR-TE does not solely rely on these shortest paths. Instead, SR-TE can override IGP decisions by enforcing explicit routes to meet specific engineering goals.

• B. Dynamic rules: Although some traffic engineering solutions adjust routes dynamically based on network conditions, SR-TE primarily uses static explicit paths defined by explicit maps. Dynamic changes are not the main method for steering traffic in SR-TE.

• C. Path policy: Path policies define general criteria or constraints (like bandwidth or priority) for route selection, but they do not specify the exact path. Explicit maps are the actual mechanism that enforces the path.

In summary, SR-TE’s ability to precisely steer traffic flows is made possible by explicit maps that outline predetermined routes, making D the correct answer. This explicit path definition improves network flexibility and efficiency by allowing administrators to tailor traffic flows to meet performance and resource objectives.

Question 8:

What is a common reason two devices might fail to form an OSPF neighbor relationship?

A. The devices have different OSPF process IDs
B. The devices have mismatched network types
C. The devices use different router IDs
D. The devices belong to the same OSPF area

Answer: B

Explanation:

Open Shortest Path First (OSPF) is a widely used link-state routing protocol designed to share routing information efficiently within an autonomous system. A fundamental step in OSPF operation is establishing neighbor relationships, which allows routers to exchange link-state information and build a consistent network topology.

For two OSPF routers to become neighbors, certain configuration parameters must match on the connecting interfaces. When these parameters differ, neighbor formation fails. Among these parameters, network type compatibility is crucial.

Let’s explore why mismatched network types cause failure and why other options do not:

• B. Different network types: OSPF supports multiple network types (broadcast, point-to-point, non-broadcast, etc.), each with distinct behaviors for neighbor discovery and packet exchanges. If two devices on the same link have different network types configured, they will not be able to synchronize and form neighbors. For example, one device configured for broadcast Ethernet expects to use multicast Hello packets for neighbor discovery, whereas a device configured for point-to-point expects a different communication method. This mismatch breaks neighbor formation.

• A. Different process IDs: The OSPF process ID is a local identifier used internally on each router and does not need to match across neighbors. Routers with different process IDs can still form neighbor relationships as long as other parameters are compatible.

• C. Different router IDs: Router IDs uniquely identify routers in the OSPF domain but do not have to match for neighbor relationships to be established. Each router must have a unique router ID, and neighbors use these to identify each other.

• D. Same area ID: Neighbors must belong to the same area to form adjacency, so having the same area ID is required, not a reason for failure. If the area IDs differ, neighbor formation fails, but the question refers to the cause of failure, making this option incorrect.

In conclusion, the failure to establish OSPF neighbor relationships most commonly occurs due to mismatched network types, making option B the correct answer. Ensuring consistent network type configurations is vital for successful OSPF adjacency.

Question 9:

Which routing protocol supports both IPv4 and IPv6 and uses a link-state algorithm to calculate the best path in an enterprise network?

A. EIGRP
B. OSPFv3
C. BGP
D. RIPv2

Correct Answer: B

Explanation:

OSPFv3 (Open Shortest Path First version 3) is the link-state routing protocol designed specifically to support both IPv4 and IPv6 routing. It evolved from OSPFv2, which was originally only capable of handling IPv4 addresses.

OSPFv3 operates by exchanging link-state advertisements (LSAs) between routers to build a complete topology map of the network. Each router independently calculates the shortest path tree using Dijkstra’s algorithm, which ensures that all routers have a synchronized view of the network, leading to fast convergence and loop-free routing.

Option A, EIGRP (Enhanced Interior Gateway Routing Protocol), supports both IPv4 and IPv6 but uses a hybrid routing algorithm (a combination of distance-vector and link-state characteristics). While EIGRP is efficient, it is not purely link-state like OSPF.

Option C, BGP (Border Gateway Protocol), is primarily an exterior gateway protocol used between autonomous systems. It is path-vector-based and does not use a link-state algorithm.

Option D, RIPv2 (Routing Information Protocol version 2), is a distance-vector protocol limited to IPv4. It uses hop count as the metric and has slow convergence, making it less suitable for modern enterprise networks.

Choosing OSPFv3 ensures compatibility with IPv6 networks and leverages the advantages of a link-state protocol, including scalability and rapid adaptation to network changes. This makes it a core technology for enterprises migrating to IPv6 or operating dual-stack environments, which is a key focus of the Cisco 300-510 exam.

Question 10:

In a Cisco SD-Access fabric, which component is responsible for mapping user identities and devices to their network policies?

A. Control Plane Node
B. Edge Node
C. Cisco Identity Services Engine (ISE)
D. Fabric Border Node

Correct Answer: C

Explanation:

In a Cisco SD-Access (Software-Defined Access) architecture, the Cisco Identity Services Engine (ISE) plays a critical role in security and policy enforcement by mapping user identities and devices to the appropriate network policies.

ISE acts as a centralized policy controller and provides capabilities such as authentication, authorization, and accounting (AAA). It gathers endpoint information, validates user credentials, and applies network access policies based on identity, device type, and security posture. These policies determine the level of network access a user or device receives within the fabric, such as access to specific VLANs, segments, or services.

Option A, the Control Plane Node, handles routing and control information within the fabric but does not manage user identity or policy mapping.

Option B, the Edge Node, is responsible for connecting end devices to the fabric and enforcing policies at the network edge, but it relies on policy decisions from ISE.

Option D, the Fabric Border Node, provides connectivity between the SD-Access fabric and external networks but is not involved in identity or policy mapping.

Understanding the role of ISE is fundamental to securing SD-Access environments, as it integrates network security with identity management, which helps reduce the attack surface and enforce granular access controls. This knowledge aligns with the Cisco 300-510 exam’s focus on security and automation within enterprise networks.