Cisco 300-510 Practice Test Questions, Exam Dumps

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300-510 Cisco Practice Test Questions and Exam Dumps

Question No 1:

Refer to the exhibit. After you applied these configurations to routers R1 and R2, the two devices could not form a neighbor relationship. Which reason for the problem is the most likely?

A. The two routers cannot authenticate with one another.
B. The two routers have the same area ID.
C. The two routers have the same network ID.
D. The two routers have different IS-types.

Answer: D

Explanation:

In the context of OSPF (Open Shortest Path First) routing, there are several reasons why two routers might fail to form a neighbor relationship. Let's explore each option:

Option A: The two routers cannot authenticate with one another.

Authentication issues can indeed prevent routers from forming OSPF neighbor relationships. However, if authentication were the problem, you would typically see an error related to authentication failure or mismatched authentication types or keys. Since this is not mentioned in the exhibit, we can rule out this possibility.

Option B: The two routers have the same area ID.

The area ID in OSPF is a logical partition of the OSPF routing domain, and it is important that OSPF routers within the same area have the same area ID. However, if two routers are in the same area (which is not necessarily a problem), they can still form a neighbor relationship if all other OSPF parameters match. Therefore, having the same area ID is not likely the cause of the issue.

Option C: The two routers have the same network ID.

In OSPF, the network ID (which refers to the network's IP address) is used to identify networks on which routers are connected. If two routers were configured on the same network segment with the same network ID, they should still be able to form a neighbor relationship. However, the issue described in the exhibit isn't directly related to the same network ID. The most likely problem would not be the network ID itself, but other configuration factors.

Option D: The two routers have different IS-types.

IS-types (Intermediate System types) in OSPF refer to the OSPF router types, such as Internal Router (IR), Area Border Router (ABR), Backbone Router (BR), and so on. In OSPF, neighbor relationships can only be established between routers that have the same IS-type. If R1 and R2 have different IS-types (for example, one being an ABR and the other being a router within the area), OSPF will not be able to form a neighbor relationship between them.

This configuration mismatch is the most likely cause of the issue described. It is critical that the routers' OSPF types align for them to form a successful neighbor relationship.

Therefore, the most likely reason the two routers cannot form a neighbor relationship is Option D: The two routers have different IS-types.

Question No 2:

Refer to the exhibit. Which effect of this configuration is true?

A. It sets the keepalive timer to 30 seconds and the hold timer to 240 seconds.
B. It sets the keepalive timer to 30 milliseconds and the hold timer to 240 milliseconds.
C. It sets the hold timer to 30 milliseconds and the keepalive timer to 240 milliseconds.
D. It sets the hold timer to 30 seconds and the keepalive timer to 240 seconds.

Correct answer: A

Explanation:

In networking, especially with protocols such as OSPF or BGP, keepalive timers and hold timers play a significant role in managing the state of a connection between routers or devices. These timers control how frequently hello packets are sent (keepalive) and how long the device waits before considering the connection down if no packets are received (hold).

Keepalive timer: This timer is used to define the interval at which the device sends a "keepalive" message to ensure the link or connection is still active.
Hold timer: This timer defines the duration the device waits to consider a peer as dead or unreachable if it doesn't receive any keepalive or hello packets during that period.

Now, let's break down the options:

Option A: "It sets the keepalive timer to 30 seconds and the hold timer to 240 seconds."
This option is consistent with the commonly used settings in networking protocols like OSPF or BGP, where the keepalive timer is usually set to a lower value (e.g., 30 seconds) and the hold timer is set to a larger value (e.g., 240 seconds).

Keepalive timer = 30 seconds

Hold timer = 240 seconds
This configuration ensures that the router checks the connection status every 30 seconds and waits up to 240 seconds before declaring the neighbor unreachable.

Option B: "It sets the keepalive timer to 30 milliseconds and the hold timer to 240 milliseconds."
This option is incorrect because it suggests a very short time frame (milliseconds) for both the keepalive and hold timers. In most networking protocols, these timers are configured in seconds, not milliseconds, because connections usually do not require such rapid checks.
Option C: "It sets the hold timer to 30 milliseconds and the keepalive timer to 240 milliseconds."
Similar to Option B, this option sets impractically small values for the timers. Again, milliseconds are too short for these types of timers in typical network configurations.
Option D: "It sets the hold timer to 30 seconds and the keepalive timer to 240 seconds."
This option is also incorrect. Normally, the hold timer should be longer than the keepalive timer to ensure that the connection is only marked as down after multiple failed keepalive attempts. In this case, the hold timer is set to 30 seconds, which would be too short compared to the standard practice of having the hold timer set to 240 seconds.

The correct interpretation of the configuration from the exhibit would be that it sets the keepalive timer to 30 seconds and the hold timer to 240 seconds, making Option A the correct answer.

Question No 3:

Refer to the exhibit. A network operator is working to filter routes from being advertised that are covered under an aggregate announcement. The receiving router of the aggregate announcement block is still getting some of the more specific routes plus the aggregate.

Which configuration change ensures that only the aggregate is announced now and in the future if other networks are to be added?

A. Configure the summary-only keyword on the aggregate command
B. Set each specific route in the AGGRO policy to drop instead of suppress-route
C. Filter the routes on the receiving router
D. Set each specific route in the AGGRO policy to remove instead of suppress-route

Correct answer: A

Explanation:

When an aggregate route is advertised, it summarizes multiple specific routes into a single, broader route to simplify routing tables and improve scalability. However, in certain cases, you may want to ensure that only the aggregate route is advertised and not the more specific routes that fall under that aggregate.

In this scenario, the receiving router is still receiving more specific routes along with the aggregate route. This typically happens when the specific routes are not properly suppressed or filtered, allowing them to still be sent to the peer.

The correct configuration change to ensure that only the aggregate route is advertised — both now and in the future — is to configure the summary-only keyword on the aggregate command. By using the summary-only keyword, the router will advertise only the aggregated summary route and prevent the more specific routes from being advertised. This option is designed specifically to address the issue where specific subnets are unnecessarily advertised along with the aggregate.

Why the other options are incorrect:

B. Set each specific route in the AGGRO policy to drop instead of suppress-route:
This option could work in some cases, but it is not the most efficient solution. Setting each specific route to "drop" manually requires more configuration and may be prone to errors, especially as new networks are added in the future. It's more appropriate to use the summary-only keyword, which ensures that only the aggregate route is advertised automatically.
C. Filter the routes on the receiving router:
While this option might work for filtering the specific routes from being accepted by the receiving router, it does not address the root cause of the problem, which is the advertisement of specific routes by the sending router. Filtering on the receiving router only mitigates the issue but does not resolve it from the source, where the aggregate advertisement should be configured to suppress the more specific routes.
D. Set each specific route in the AGGRO policy to remove instead of suppress-route:
The remove action in the policy is intended to delete specific routes from the routing table. However, this is not the same as ensuring that only the aggregate route is advertised. Using summary-only would be a more straightforward and effective solution to prevent the specific routes from being advertised in the first place.

Therefore, the best approach is A, configuring the summary-only keyword on the aggregate command, which ensures that only the aggregate route is advertised, keeping the routing table clean and simple.

Question No 4:

Refer to the exhibit. A network operator is getting the route for 10.11.11.0/24 from two upstream providers on #XR3. The network operator must configure #XR3 to force the 10.11.11.0/24 prefix to route via next hop of 10.0.0.9 as primary when available.

Which of these can the operator use the routing policy language for, to enforce this traffic forwarding path?

A. weight of 0 on the prefix coming from 192.168.0.2
B. lower local preference on the prefix coming from 192.168.0.2
C. higher local preference on the prefix coming from 192.168.0.1
D. weight of 100 on the prefix coming from 192.168.0.1

Correct answer: C

Explanation:

To control the routing path for the 10.11.11.0/24 prefix in this situation, the network operator needs to manipulate the BGP path selection process in order to prioritize the next hop 10.0.0.9 as the primary route when it is available.

BGP uses several attributes to determine the best path to a destination, and one of the most significant attributes is local preference. Local preference is a BGP attribute used within an Autonomous System (AS) to determine the preferred outbound path. Higher values for local preference indicate a higher preference for the route, so in this case, the operator wants to increase the local preference for the route coming from 192.168.0.1, as this route corresponds to the next hop of 10.0.0.9, which is the desired primary path.

Let’s evaluate the options:

Option A: weight of 0 on the prefix coming from 192.168.0.2 – The weight attribute is a Cisco-specific attribute that is only relevant to the local router and does not propagate to other routers. Setting the weight of the prefix coming from 192.168.0.2 to 0 would not force the preferred path to 10.0.0.9. In fact, the weight is irrelevant here since the objective is to prioritize local preference for routing.

Option B: lower local preference on the prefix coming from 192.168.0.2 – This would make the prefix coming from 192.168.0.2 less preferred. While lowering local preference for this route might push the path from 192.168.0.1 as the preferred one, the more effective approach would be to raise the local preference for the prefix from 192.168.0.1, not lower it for the other path.

Option C: higher local preference on the prefix coming from 192.168.0.1 – This is the correct approach. By increasing the local preference for the prefix received from 192.168.0.1, the network operator forces the traffic to prefer the path that leads to 10.0.0.9 (which is the desired next hop) whenever both routes are available. Local preference is a widely used method for manipulating the preferred path within an AS.

Option D: weight of 100 on the prefix coming from 192.168.0.1 – While setting the weight on this route would increase its preference locally on #XR3, the weight attribute would not affect BGP decision-making across the entire AS. The more appropriate and consistent method for controlling routing decisions in this case would be to manipulate the local preference rather than relying on the weight, which is local to the router.

Therefore, the best solution to force the primary path through 10.0.0.9 when available is to increase the local preference on the prefix coming from 192.168.0.1, which corresponds to the desired next hop. Hence, the correct answer is C.

Question No 5:

Refer to the exhibit. After troubleshooting an OSPF adjacency issue, routers 1, 2, and 3 have formed OSPF neighbor relationships. Which statement about the configuration is true?

A. Router 2 receives a Type 5 LSAs from router 1 for its connected subnets
B. Router 2 uses router 3 as the next hop for 192.168.0.0/24
C. Router 2 uses router 1 as the next hop for 192.168.0.0/24
D. Router 2 receives a Type 7 LSAs from router 3 for its connected subnets

Correct answer: C

Explanation:

The Open Shortest Path First (OSPF) protocol is a link-state routing protocol that allows routers to exchange routing information with each other. Each router in the OSPF domain advertises its routes in the form of Link State Advertisements (LSAs), which allow routers to learn about each other's networks and build an accurate routing table. Depending on the network configuration, the types of LSAs exchanged and the routing paths chosen can vary.

A. Router 2 receives a Type 5 LSAs from router 1 for its connected subnets is incorrect. A Type 5 LSA, also known as an external LSA, is used in OSPF to advertise routes to external destinations, such as networks outside the OSPF domain. This would typically be generated by an Autonomous System Boundary Router (ASBR) to advertise external routes, but it is not applicable to connected subnets within the OSPF domain. The question does not indicate the presence of an ASBR, so this is not the correct choice.

B. Router 2 uses router 3 as the next hop for 192.168.0.0/24 is incorrect. The next hop for a route is determined by the OSPF routing table, which is based on the exchange of LSAs between neighbors. If routers 1, 2, and 3 have formed an OSPF adjacency, router 2 will most likely use router 1 as the next hop for the 192.168.0.0/24 network, assuming router 1 is directly connected to that network or is advertising it within the OSPF domain. Router 3 would only be used if it is part of the best path for this network, which is unlikely in this context.

C. Router 2 uses router 1 as the next hop for 192.168.0.0/24 is correct. Based on the OSPF adjacency formed between routers 1, 2, and 3, router 2 would use router 1 as the next hop for the 192.168.0.0/24 network. This is because router 1 is likely advertising that subnet, and router 2 has formed an OSPF adjacency with router 1. The next hop for any route in OSPF is typically the router directly connected to the destination, or the router that provides the best path for that destination. In this case, router 1 is the most likely next hop for the 192.168.0.0/24 subnet.

D. Router 2 receives a Type 7 LSAs from router 3 for its connected subnets is incorrect. Type 7 LSAs are used in OSPF for Not-So-Stubby Areas (NSSAs). They are typically generated by an ASBR in NSSAs to advertise external routes. Since this question does not specify an NSSA configuration or an ASBR, it is unlikely that router 2 is receiving Type 7 LSAs from router 3 for its connected subnets.

In conclusion, the most accurate statement about the OSPF configuration based on the exhibit is that router 2 uses router 1 as the next hop for the 192.168.0.0/24 network. This is the most common routing behavior in a simple OSPF adjacency setup.

Question No 6:

A network consultant is troubleshooting IS-IS instances to identify why a routing domain is having communication problems between the two instances.

Which description of the possible cause of issues in the routing domain is true?

A. The same interface cannot be advertised in two different IS-IS instances
B. The IS-IS "ISP" and "ISP2" instances are unrelated and unable to intercommunicate
C. The configured IS-IS NSEL value is not allowing the routing systems to establish a neighborship
D. The interface mode ip router is-is command was not included in the script

The correct answer is A.

Explanation:

When troubleshooting IS-IS (Intermediate System to Intermediate System) instances and their communication within a routing domain, there are several factors that can affect the neighborship and overall communication between the instances. In this case, the correct answer is A, which indicates that the same interface cannot be advertised in two different IS-IS instances.

A is correct because, in IS-IS, an interface can only belong to one IS-IS instance at a time. If the same interface is assigned to two different instances, it will cause conflicts, as each instance expects to have exclusive control over the interface for advertising and establishing neighbor relationships. This can prevent communication between the routing domains that rely on the IS-IS instances.
B is incorrect. IS-IS instances, such as "ISP" and "ISP2", can be configured independently to represent different routing domains. However, as long as the interfaces are configured properly and the correct policies are in place, they can communicate with each other across different IS-IS instances. Instances themselves do not inherently block intercommunication unless explicitly configured not to do so.
C is not entirely accurate. The NSEL (Network Service Access Point Selector) value is a key part of IS-IS address configurations, but communication issues related to NSEL values are typically not the first cause to check unless there are specific address mismatches. NSEL typically affects service access points rather than the basic establishment of neighborships. Other configuration issues (like interface assignment) are more likely to be the root cause.
D is also not the most likely explanation. While the "ip router is-is" command is essential to enable IS-IS on the router's interfaces, this command typically appears as part of interface configuration and would more likely prevent any IS-IS operation if omitted, not cause issues between two instances.

Thus, the correct answer is A.

Question No 7:

What is used by SR-TE to steer traffic through the network?

A. shortest path calculated by IGP
B. dynamic rules
C. path policy
D. explicit maps

Answer: D

Explanation:

Segment Routing Traffic Engineering (SR-TE) is a mechanism that enables the network to steer traffic through predefined, deterministic paths, without relying on traditional signaling protocols such as Resource Reservation Protocol (RSVP). The key feature of SR-TE is that it allows the control of traffic flows based on specific paths, and these paths are determined using explicit instructions.

D. explicit maps: The correct answer. In SR-TE, traffic is steered through the network using explicit maps, also known as SR policies or explicitly defined paths. These maps define the exact sequence of segments (or hops) that traffic should follow across the network. Explicit maps are manually or automatically configured and are used to define specific, predetermined routes for traffic, which can optimize network resources or meet certain performance requirements. These paths are not dynamic but are static and predefined by network administrators, ensuring predictable and reliable traffic engineering.

Now, let’s review why the other options are incorrect:

A. shortest path calculated by IGP: While IGP (Interior Gateway Protocol) such as OSPF or IS-IS calculates the shortest path in a network based on topology, SR-TE does not rely on the IGP's shortest path calculation to steer traffic. Instead, SR-TE uses predefined explicit paths that may or may not align with the IGP's shortest path. SR-TE gives the flexibility to define paths that can optimize for various parameters like bandwidth, latency, or network topology, which may not coincide with the shortest IGP path.
B. dynamic rules: Dynamic rules might refer to policies that change based on real-time conditions or metrics, but this is not the core method used by SR-TE to steer traffic. SR-TE typically operates based on predefined, static paths (explicit maps), and while traffic engineering can use dynamic metrics to influence path selection, the traffic is ultimately steered through static, explicit paths rather than dynamic rules.
C. path policy: Although path policies can be used to define various attributes of traffic engineering (like bandwidth, latency, or preferred path), SR-TE specifically uses explicit maps to direct traffic. Path policies are related to the overall traffic engineering strategy, but they are not the primary mechanism for steering traffic in SR-TE.

In conclusion, SR-TE uses explicit maps to direct traffic through specific, predefined paths across the network, making option D the correct choice. These explicit maps allow for precise control over the path traffic takes, enhancing the flexibility and efficiency of network traffic management.

Question No 8:

For which reason can two devices fail to establish an OSPF neighbor relationship?

A. The two devices have different process IDs
B. The two devices have different network types
C. The two devices have different router IDs
D. The two devices have the same area ID

Correct answer: B

Explanation:

Open Shortest Path First (OSPF) is a link-state routing protocol that relies on specific parameters being consistent across devices in order to form successful neighbor relationships. If any of these parameters do not match, the devices will fail to establish a neighbor relationship. Let's analyze the options to determine which one would prevent OSPF neighbors from forming.

A. The two devices have different process IDs: OSPF process IDs are local to each router and are used to distinguish between multiple OSPF processes running on the same router. The process ID does not impact the ability to form an OSPF neighbor relationship between two devices, as OSPF neighbors only need to share the same area ID and other key parameters, but not process IDs.
B. The two devices have different network types: This is the correct answer. OSPF network types (e.g., broadcast, point-to-point, non-broadcast, etc.) must match between devices in order to establish a neighbor relationship. If two devices are configured with different network types on the same link, they will not be able to communicate and form an OSPF neighbor relationship. For instance, a device with a broadcast network type (e.g., Ethernet) cannot form a neighbor relationship with a device configured for a point-to-point network type unless specific adjustments are made.
C. The two devices have different router IDs: The router ID is used by OSPF to uniquely identify routers within the network. However, routers can still form OSPF neighbor relationships even if their router IDs are different, as long as other configuration parameters are correct (e.g., area ID, network type). The router ID does not prevent the formation of a neighbor relationship directly.
D. The two devices have the same area ID: The area ID is used to segment the OSPF network into different areas. Devices in the same area can form neighbor relationships as long as other parameters align. Having the same area ID is a requirement for forming a neighbor relationship, not a reason for failure. If the area ID is different between two devices, they will fail to form a neighbor relationship, but the same area ID is necessary and valid.

Thus, the correct reason for OSPF neighbor relationship failure is B, as the devices must have the same network type for successful OSPF neighbor formation.