Cisco 300-630 Practice Test Questions, Exam Dumps

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300-630 Cisco Practice Test Questions and Exam Dumps

Question No 1:

Refer to the exhibit. How is the ARP request from VM1 forwarded when VM2 is not learned in the Cisco ACI fabric?

A. Leaf 101 forwards the ARP request to one of the proxy VTEP spines.
B. POD1 spine responds to the ARP request after the POD1 COOP is updated with the VM2 location.
C. Leaf 101 encapsulates the ARP request into a multicast packet that is destined to 225.0.37.192.
D. Leaf 101 switch consumes the ARP reply of VM2 to update the local endpoint table.

Correct answer: C

Explanation:

In Cisco ACI (Application Centric Infrastructure), when an endpoint such as VM2 is not learned locally, the ARP request from VM1 needs to be forwarded to find the MAC address of VM2. Since VM2 is not yet learned, Leaf 101 encapsulates the ARP request into a multicast packet that is sent to the multicast address 225.0.37.192. This multicast address is part of the standard method used in ACI for unknown destination endpoint lookup.

This method allows the ARP request to be flooded to all ACI nodes that are capable of forwarding traffic for that subnet. The appropriate leaf switches will then be able to respond with the required information, including the MAC address of VM2.

Here’s why the other options are incorrect:

A. Leaf 101 forwards the ARP request to one of the proxy VTEP spines: This is not correct because the ARP request is not specifically forwarded to a proxy VTEP. Instead, the fabric relies on multicast forwarding for unknown endpoint lookups.
B. POD1 spine responds to the ARP request after the POD1 COOP is updated with the VM2 location: This is not how the ARP request is handled in ACI. The spine does not directly respond to the ARP request. The request is multicast, and the response is provided by the appropriate leaf switch.
D. Leaf 101 switch consumes the ARP reply of VM2 to update the local endpoint table: This statement describes what happens once the ARP reply is received, but it does not explain how the initial ARP request is forwarded in the absence of VM2 in the local endpoint table. The request is sent out via multicast, not simply consumed locally.

Therefore, the correct action is C, where the ARP request is encapsulated and sent as a multicast packet.

Question No 2:

Which approach does Cisco ACI use to achieve multi destination packet forwarding between leaf switches in the same fabric?

A. Map VXLAN VTEP to the multicast group
B. Map VXLAN to PIM-SM protocol
C. Map VXLAN VNI to the multicast group
D. Map VXLAN to PIM-DM protocol

Correct Answer: C

Explanation:

In Cisco ACI (Application Centric Infrastructure), multidestination packet forwarding between leaf switches within the same fabric is typically handled by leveraging VXLAN (Virtual Extensible LAN) technology. VXLAN uses multicast to efficiently distribute traffic between multiple leaf switches in a fabric.

The method used by Cisco ACI to achieve this involves mapping the VXLAN Network Identifier (VNI) to a multicast group. This allows the fabric to handle broadcast, unknown unicast, and multicast (BUM) traffic efficiently. When a packet needs to be forwarded to multiple destinations (i.e., to several leaf switches or endpoints within the same VNI), the fabric uses multicast forwarding based on the multicast group mapped to the VNI. This mapping ensures that the correct multicast traffic is forwarded to all relevant leaf switches in the fabric.

Here’s why the other options are incorrect:

Option A suggests mapping VXLAN VTEP (VXLAN Tunnel Endpoint) to a multicast group. While VXLAN does use VTEPs to handle encapsulation and forwarding of packets, this option is not the primary method for achieving multidestination forwarding within Cisco ACI. It is the VNI-to-multicast mapping that plays the key role in efficient forwarding, not directly the VTEPs.
Option B suggests mapping VXLAN to PIM-SM (Protocol Independent Multicast Sparse Mode). Although PIM-SM is used in some multicast environments, Cisco ACI typically uses native VXLAN with multicast rather than relying on PIM-SM for forwarding.
Option D refers to mapping VXLAN to PIM-DM (Protocol Independent Multicast Dense Mode). Like PIM-SM, PIM-DM is another multicast routing protocol, but it is not used in Cisco ACI for the purpose of mapping VXLAN to multicast groups. Cisco ACI’s multicast traffic forwarding is simpler, focusing on VXLAN VNI to multicast group mapping rather than using PIM protocols.

Thus, the correct approach is to map VXLAN VNI to the multicast group, making C the correct answer.

Question No 3:

What does the VXLAN source port add to the overlay packet forwarding when it uses the hash of Layer 2, Layer 3, and Layer 4 headers of the inner packet?

A. ECMP
B. TCP optimization
C. disabled fragmentation
D. jumbo frames

Correct answer: A

Explanation:

In a VXLAN (Virtual Extensible LAN) setup, the source port is used in conjunction with the hash of the inner packet headers (Layer 2, Layer 3, and Layer 4) to influence the forwarding decision. This approach helps determine how packets are distributed across multiple paths in the network, improving the load balancing mechanism.

ECMP (Equal-Cost Multi-Path) (Option A):
This is the correct answer. VXLAN uses the source port and the hash of the inner packet's headers (including Layer 2, Layer 3, and Layer 4) to perform load balancing across multiple paths. By calculating a hash, VXLAN can make forwarding decisions that allow for ECMP. This means that traffic can be spread across multiple equal-cost paths, which helps improve network efficiency, reliability, and redundancy. The hash function helps ensure that traffic flows consistently across the same path, thus enabling load balancing across multiple equal-cost paths without the risk of packet reordering.
TCP optimization (Option B):
This is incorrect. VXLAN source ports and the hash of the inner packet headers do not directly provide TCP optimization. TCP optimization typically focuses on improving the efficiency of TCP connections, such as minimizing latency or increasing throughput, but this is not the role of the VXLAN source port or the hash used in overlay packet forwarding.
Disabled fragmentation (Option C):
This option is not correct. VXLAN does not use the hash of the inner packet headers to control fragmentation behavior. VXLAN itself may involve encapsulation that could require handling of larger packets, but fragmentation is managed independently of the hash function used for forwarding.
Jumbo frames (Option D):
This is also incorrect. While jumbo frames refer to the ability to transmit larger Ethernet frames, the use of the source port and the hash of the inner headers does not directly impact the handling of jumbo frames. VXLAN itself may allow for larger frames to be transmitted, but it does not specifically add jumbo frame support through the hash function.

In conclusion, the source port and the hash of the inner packet headers in VXLAN contribute to ECMP (Equal-Cost Multi-Path), enabling more efficient traffic distribution and improved load balancing in the overlay network.

Question No 4:

Which two actions are the Cisco best practices to configure NIC teaming load balancing for Cisco UCS B-Series blades that are connected to the Cisco ACI leaf switches? (Choose two.)

A. Create vPC+
B. Enable LACP active mode
C. Create PAgP
D. Create vPC
E. Enable MAC pinning

Correct answer: B, D

Explanation:

When configuring NIC teaming load balancing for Cisco UCS B-Series blades connected to Cisco ACI leaf switches, it is crucial to use the right protocols and configurations to ensure efficient distribution of traffic across multiple physical network links.

B. Enable LACP active mode: LACP (Link Aggregation Control Protocol) is essential for NIC teaming as it dynamically manages link aggregation. Enabling LACP in active mode allows the switch to negotiate link aggregation and optimize load balancing across the links in the team. Active mode ensures that the UCS blade and the ACI leaf switch can correctly establish an LACP aggregation, allowing traffic to be distributed across the available links.
D. Create vPC: vPC (Virtual Port Channel) is another best practice in Cisco ACI environments. It allows the use of multiple links from the UCS blades to the ACI leaf switches without creating a loop in the network. A vPC enables the aggregation of links while presenting a single logical link to the UCS blade, which allows better load balancing and fault tolerance. By creating a vPC, the UCS blades can distribute traffic efficiently across the available physical connections to the leaf switches.

Let’s analyze the other options:

A. Create vPC+: vPC+ is used when configuring Cisco Nexus switches in a fabric with vPCs. However, vPC is the primary and most commonly used option for standard configurations. vPC+ is an advanced feature that is often not required unless specific advanced configurations are needed, such as in a multi-fabric environment.
C. Create PAgP: PAgP (Port Aggregation Protocol) is an older protocol used to negotiate link aggregation in some Cisco environments. However, LACP is the preferred and more widely used protocol in modern configurations, especially in environments like Cisco ACI.
E. Enable MAC pinning: MAC pinning is typically used in scenarios with VMware vSphere for static port-to-MAC address mappings in vSwitch configurations. It is not a best practice for NIC teaming load balancing in Cisco UCS B-Series blades connected to ACI leaf switches.

Thus, the best actions for enabling NIC teaming load balancing in this scenario are B (Enable LACP active mode) and D (Create vPC).

Question No 5:

An organization migrates its virtualized servers from a legacy environment to Cisco ACI. VM1 is incorrectly attached to PortGroup IT|3TierApp|Web. Which action limits IP address learning in BD1?

A. Enable Enforce Subnet Check
B. Enable Rouge Endpoint Control
C. Enable GARP-based EP Move Detection Mode
D. Disable Remote EP Learn

Correct answer: A

Explanation:

In Cisco ACI, IP address learning is a key part of managing endpoints within a Bridge Domain (BD). When an endpoint (such as VM1) is incorrectly placed in a BD or PortGroup, the ability to limit or control IP address learning is important to avoid issues with traffic forwarding.

Option A: Enable Enforce Subnet Check is the correct action in this case. Enabling the Enforce Subnet Check feature ensures that endpoints are only allowed to communicate if they are within the defined subnet for that Bridge Domain (BD). If VM1 is attached to a PortGroup that is incorrectly associated with BD1, enabling this feature would limit or prevent IP address learning for VM1, effectively containing the problem to the correct subnet.

Option B: Enable Rogue Endpoint Control helps manage endpoints that appear in the network but are not authorized or expected. It provides control over unauthorized devices, but it does not specifically address limiting IP address learning within a BD.

Option C: Enable GARP-based EP Move Detection Mode is used to detect endpoint moves based on Gratuitous ARP (GARP) messages. While it can help in environments where endpoints change their location, it does not limit IP address learning in a Bridge Domain; it is more about detecting and handling moves of already known endpoints.

Option D: Disable Remote EP Learn prevents the learning of remote endpoints (those not directly attached to the local switch). While this can be useful in specific topologies, it does not directly address the problem of incorrectly placed endpoints or the limitation of IP address learning within BD1 in this context.

Thus, the correct action is A, to enable Enforce Subnet Check to limit IP address learning in BD1 and prevent communication from incorrectly placed endpoints like VM1.

Question No 6:

Refer to the exhibit. What must be configured to allow the PBR node (LB-int) to monitor the availability of the endpoint that is in the EPG server?

A. Endpoint Dataplane Learning
B. Unicast Route disabled for client and server bridge domains
C. PBR node tracking
D. Direct Connect in the service graph template

Correct answer: C

Explanation:

In the context of Policy-Based Routing (PBR) and monitoring endpoint availability, it is essential for the PBR node (in this case, LB-int) to track the state or availability of the endpoints in the relevant Endpoint Groups (EPGs). This allows the PBR node to adjust traffic flows based on the current reachability of the destination endpoint, ensuring optimized routing decisions.

A. Endpoint Dataplane Learning is not directly related to the availability monitoring of endpoints by the PBR node. Endpoint dataplane learning is more about discovering endpoints and learning their locations in the network, but it does not specifically focus on monitoring the availability or health of the endpoints in real-time for routing purposes.

B. Unicast Route disabled for client and server bridge domains is incorrect. Disabling unicast routes in bridge domains is a network design consideration related to traffic forwarding, but it does not specifically relate to enabling monitoring of endpoint availability for PBR nodes. This configuration would not resolve the problem of tracking endpoint health for PBR.

C. PBR node tracking is the correct answer. PBR node tracking enables the PBR device to monitor the health and availability of the endpoint in the EPG server. By configuring tracking on the PBR node, it can dynamically adapt the routing behavior based on whether the endpoint is reachable, which is crucial for the effective implementation of Policy-Based Routing. This allows the PBR node to adjust its policies according to the endpoint’s availability.

D. Direct Connect in the service graph template is incorrect. While Direct Connect is used in service graph templates to establish connectivity between devices or functions, it is not directly related to monitoring the availability of endpoints for PBR purposes. It focuses more on the network topology and connections between services, not on monitoring endpoint health for routing decisions.

In summary, to enable the PBR node to monitor the availability of an endpoint in the EPG server, configuring PBR node tracking is necessary. This ensures that the node can adjust traffic flows based on real-time endpoint reachability.

Question No 7:

An engineer must limit local and remote endpoint learning to the bridge domain subnet. Which action should be taken inside the Cisco APIC?

A. Disable Remote EP Learn
B. Enable Enforce Subnet Check
C. Disable Endpoint Dataplane Learning
D. Enable Limit IP Learning to Subnet

Correct answer: D

Explanation:

To restrict both local and remote endpoint learning to the bridge domain subnet in a Cisco ACI (Application Centric Infrastructure) environment, the correct action is to Enable Limit IP Learning to Subnet. This option limits the learning of endpoints (EPs) to the defined subnet of the bridge domain, ensuring that both local and remote endpoint learning are constrained to the appropriate subnet.

A (Disable Remote EP Learn) is incorrect because disabling remote endpoint learning doesn't directly address limiting learning to the bridge domain subnet. It only prevents learning of remote endpoints across the fabric.
B (Enable Enforce Subnet Check) is a valid consideration in some cases, but it doesn't specifically limit endpoint learning to the bridge domain subnet. It enforces a check on endpoint IP addresses, which could be useful in ensuring that endpoints are within the defined subnet, but it does not fully solve the learning restriction.
C (Disable Endpoint Dataplane Learning) is not the correct solution. Disabling dataplane learning entirely would stop learning endpoints on the dataplane altogether, which is not the goal here. We want to limit learning, not disable it.
D (Enable Limit IP Learning to Subnet) directly addresses the requirement to limit both local and remote endpoint learning to the bridge domain subnet. This ensures that the system only learns endpoints within the allowed IP address range of the bridge domain.

Thus, the correct answer is D.

Question No 8:

What is the purpose of the Forwarding Tag (FTAG) in Cisco ACI?

A. FTAG is used in Cisco ACI to add a label to the iVXLAN traffic in the fabric to apply the correct policy.
B. FTAG is used in Cisco ACI to add a label to the VXLAN traffic in the fabric to apply the correct policy.
C. FTAG trees in Cisco ACI are used to load balance unicast traffic.
D. FTAG trees in Cisco ACI are used to load balance multi-destination traffic.

Correct answer: D

Explanation:

In Cisco ACI (Application Centric Infrastructure), the Forwarding Tag (FTAG) plays a crucial role in managing how traffic is handled within the fabric, particularly in the context of multi-destination traffic (e.g., multicast and broadcast traffic). FTAGs are part of the iVXLAN (integrated VXLAN) mechanism used to identify and efficiently forward these types of traffic.

D. FTAG trees in Cisco ACI are used to load balance multi-destination traffic: This is the correct answer because FTAG trees are designed to provide load balancing for traffic that is sent to multiple destinations, such as multicast or broadcast traffic. In ACI, FTAGs are used to create an efficient forwarding structure, which allows for the distribution of multi-destination traffic across the fabric in a way that optimizes network performance and ensures traffic is directed to the appropriate destinations.

Now, let's break down the other options:

A. FTAG is used in Cisco ACI to add a label to the iVXLAN traffic in the fabric to apply the correct policy: While FTAGs are related to iVXLAN (integrated VXLAN), the primary purpose of FTAG is to assist in the load balancing and forwarding of multi-destination traffic, not to apply policies. The concept of labeling iVXLAN traffic for policy enforcement is separate from the role of FTAG in handling multi-destination traffic.
B. FTAG is used in Cisco ACI to add a label to the VXLAN traffic in the fabric to apply the correct policy: This statement is also incorrect because FTAG does not specifically label VXLAN traffic to apply policies. The primary use of FTAG is for load balancing multi-destination traffic, not for policy application.
C. FTAG trees in Cisco ACI are used to load balance unicast traffic: This is incorrect. FTAG trees are not used for unicast traffic. Unicast traffic typically follows point-to-point forwarding, and FTAG is used specifically for multi-destination traffic. Unicast traffic does not require the same kind of tree structure or load balancing as multicast or broadcast traffic.

In conclusion, FTAG trees in Cisco ACI are used to efficiently load balance multi-destination traffic, ensuring that the network can handle broadcast, multicast, and other types of traffic that require distribution to multiple endpoints. Hence, the correct answer is D.

Question No 9:

An engineer deployed a Cisco ACI fabric and noticed that the fabric learns endpoints from subnets that are not configured on a bridge domain. To meet strict security requirements, the engineer must prevent this behavior. Which action must be taken to prevent this behavior?

A. Activate Enable Data Plane Endpoint Learning
B. Implement Pervasive Gateway
C. Configure Static Binding
D. Enable Enforce Subnet Check

Correct answer: D

Explanation:

In Cisco ACI, the system is designed to learn endpoints associated with specific subnets and bridge domains. However, when the fabric learns endpoints from subnets that are not configured on a bridge domain, this can lead to security concerns, as unauthorized or unintended endpoints may be allowed to access the fabric. To address this issue and meet strict security requirements, the engineer must take action to ensure that only endpoints from the correct subnets are learned and associated with the correct bridge domains.

A. Activate Enable Data Plane Endpoint Learning: This option refers to the ability of the fabric to learn endpoints based on data plane traffic. However, this doesn't directly address the issue of preventing the learning of endpoints from unauthorized subnets. This feature is more related to the basic endpoint learning process but does not restrict which subnets are allowed.
B. Implement Pervasive Gateway: Pervasive Gateway is used to allow external devices to access the ACI fabric, typically for scenarios involving Layer 3 routing outside the fabric. It is not designed to restrict endpoint learning based on subnet configurations. Thus, it does not resolve the issue described.
C. Configure Static Binding: Static bindings are used to explicitly define which endpoint belongs to a specific bridge domain and subnet. While this can be used as a measure to control endpoint associations, it doesn't inherently prevent the fabric from learning endpoints from subnets not configured on the bridge domain. Static binding simply forces known endpoints into specific places, rather than preventing the learning of unknown endpoints.
D. Enable Enforce Subnet Check: Enabling the Enforce Subnet Check option forces the ACI fabric to only allow endpoint learning for subnets that are explicitly configured on a bridge domain. This prevents the learning of endpoints from subnets that are not part of the configured bridge domain, thereby addressing the issue and meeting the security requirements. This is the most effective solution to prevent endpoints from being learned from unauthorized subnets.

Therefore, the correct action to take is D, enabling the Enforce Subnet Check to ensure strict control over which subnets are allowed for endpoint learning in the Cisco ACI fabric.