300-630 Practice Exam Questions with Answers Implementing Cisco Application Centric Infrastructure - Advanced (DCACIA) Certification

To ensure the Cisco ACI fabric adheres to strict security protocols and only learns endpoints from configured subnets on a bridge domain, the “Enforce Subnet Check” feature must be enabled. This feature restricts endpoint learning to IP addresses belonging to the subnets defined in the bridge domain associated with the endpoint’s VLAN, enhancing security by preventing learning of endpoints from unconfigured subnets. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

 In Cisco ACI, the spines suppress STP BPDUs to prevent them from being forwarded to other pods. This behavior ensures that the ACI fabric operates efficiently without relying on STP for loop prevention.

References := Cisco APIC Layer 2 Networking Configuration Guide, Release 5.2(x)

Cisco ACI uses a mapping of VXLAN Virtual Network Identifier (VNI) to multicast groups to facilitate multidestination packet forwarding between leaf switches within the same fabric. This approach allows for efficient communication and data packet distribution to multiple destinations simultaneously1.

References := Cisco ACI Multidestination Packet Forwarding Approach

For intra-VRF transit routing between two external routers in different OSPF areas, OSPF virtual links are required. They connect non-contiguous areas to the backbone area, ensuring all areas can communicate even if not directly connected.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

In a two-site Multi-Pod deployment with an active/standby firewall pair stretched across pods, traffic is directed to the pod with the active service node. This approach ensures that all traffic goes through the firewall that is currently handling traffic, maintaining security policies consistently across both sites while also providing high availability by automatically failing over to the standby firewall in case of any issues with the active one. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

 When EPGs (Endpoint Groups) are stretched across sites, Layer 2 flooding is available across these sites. This allows for the extension of the Layer 2 domain and the sharing of broadcast, unknown unicast, and multicast traffic between EPGs at different locations.

References: = Implementing Cisco Application Centric Infrastructure Official Cert Guide

 In a stretched bridge domain solution between Cisco ACI sites with Layer 2 flood enabled, spine head-end replication is utilized to forward Broadcast, Unknown unicast, and Multicast (BUM) traffic between the sites. This method leverages the spine switches at each site to replicate BUM traffic to other sites, ensuring that all endpoints within the stretched bridge domain can receive such traffic. This approach is chosen over ISN multicast replication because it simplifies the overall design and reduces bandwidth consumption on inter-site links by avoiding unnecessary duplication of BUM traffic. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

The topology change notification (TCN) in Spanning Tree Protocol (STP) triggers a flush of the MAC address table. When a leaf node receives a TCN, it flushes the MAC address entries associated with the VLANs affected by the topology change. In this case, since the TCN is related to VLAN 101, the ACI fabric will flush all endpoints associated with VLAN 101 in bridge domain BD10123 on the leaf node.

 For the Cisco ACI leaf to learn individual MAC addresses from the same physical port, “MAC pinning” mode must be enabled in the vSwitch policy configuration. This mode allows each ESXi vSwitch port group to pin to a specific uplink or set of uplinks, enabling independent MAC address learning for each pinned uplink, which is essential for distinguishing multiple VMs on an ESXi host by the leaf switch. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

The best practices for configuring NIC teaming load balancing for Cisco UCS B-Series blades connected to Cisco ACI leaf switches involve enabling LACP (Link Aggregation Control Protocol) in active mode and enabling MAC pinning.

LACP active mode (option B) allows for the automatic bundling of several physical links into a single logical link, providing redundancy and increased bandwidth. This mode actively tests the link to ensure its functionality, which is essential for maintaining a stable connection.

MAC pinning (option E) is a method that assigns a virtual machine’s MAC address to a specific uplink. This ensures consistent forwarding paths for traffic within the same session, which is crucial for avoiding potential traffic distribution issues that could arise from dynamic changes in the network topology.

Creating vPC+ (option A) and vPC (option D) are not recommended as they are related to virtual port channels, which are not applicable in this scenario.PAgP (Port Aggregation Protocol) (option C) is Cisco’s proprietary protocol similar to LACP, but it is not the recommended practice in this context.

References :=

Implementing Cisco Application Centric Infrastructure Official Cert Guide

Cisco’s documentation on UCS B-Series Teaming Bonding Options

 In a Cisco ACI Multi-Site setup, the source leaf is responsible for flooding BUM (Broadcast, Unicast, and Multicast) traffic to the specific multicast group or GIPo (Group IP Overlay). This process involves the ingress replication function on the spine nodes of the source site to replicate BUM traffic to all remote sites where the bridge domain is stretched12.

References := Cisco ACI Multi-Site Architecture White Paper, ACI Multi-Site Data Plane Communication - DCLessons

When a host connected to a Cisco ACI fabric leaf switch sends an ARP request, the ingress leaf switch uses a broadcast transmission method to send the ARP requests. This is because ARP requests are meant to discover the MAC address associated with a specific IP address within the same network broadcast domain. The ingress leaf switch does not know the destination MAC address, so it broadcasts the ARP request to all devices within the broadcast domain1.

References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

Enabling GARP EP Move Detection allows the Cisco ACI fabric to dynamically update the IP address to use the MAC address of NIC2 when NIC1 goes offline. This feature is crucial for maintaining network connectivity and ensuring that traffic continues to flow seamlessly through the standby interface1.

 To enable communication between the subnets 192.168.1.0/24 and 172.18.1.0/24 using Cisco ACI fabric, it is necessary to configure the subnets appropriately. For option B, setting 172.18.1.0/24 as an External subnet for an external EPG under L3out_A allows it to be recognized as part of an external network, facilitating communication with other networks within the ACI environment. Similarly, for option D, configuring 172.18.1.0/24 with the Export Route Control scope under L3out_B ensures that this route is advertised out of L3out_B, allowing it to reach other network segments, including those connected via L3out_A where the subnet 192.168.1.0/24 resides. These configurations are crucial for proper routing between these two distinct subnets across the Cisco ACI fabric.

References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

Protocol Independent Multicast sparse mode (PIM-SM) is designed for efficient routing to multiple receivers in a multicast group across an inter-pod network (IPN). PIM sparse mode is best suited for environments where receivers are dispersed because it allows for explicit join messages to control the flow of traffic. This makes it ideal for scenarios where broadcast, unknown unicast, and multicast flooding between Cisco ACI pods is required. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

To support an application that is sensitive to latency and jitter, it is crucial to ensure that the Quality of Service (QoS) levels within the ACI fabric and the Inter-Pod Network (IPN) QoS policies are aligned. This alignment will help in maintaining consistent handling of the DSCP values set by the application (AF31 and CS6) as the packets traverse across the two ACI pods. By aligning the QoS levels and policies, the application’s packets are less likely to experience delays or drops, thus preserving the required performance levels for the application’s optimal functionality.

 To address loops detected from endpoints in a Cisco ACI fabric, the engineer should enable the rogue endpoint feature and set the Error Disabled Recovery Policy. This will allow the system to detect rogue endpoints causing loops and automatically recover the port if it was disabled due to the loop detection2.

References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

For shared L3Out network connectivity among different tenants in a Cisco ACI fabric, a common tenant is necessary. It provides a global space for defining resources like L3Outs once, which can then be utilized by multiple tenants, simplifying management and ensuring consistent policy application. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

 In Cisco ACI, contracts define the policies for communication between EPGs (Endpoint Groups). For a client in WebClient EPG to establish an HTTP connection toward a server in WebServer EPG, the contract must allow the initiation of communication from WebClientto WebServer. Since HTTP uses port 80, the destination port (DST Port) should be set to 80 as per standard HTTP communications. The option “Apply Both Direction DISABLED” means that only the initiator of the connection (in this case, WebClient EPG) can send traffic unless specified otherwise by another contract or filter. The “Reverse Port Filter ENABLED” allows return traffic from WebServer EPG back to WebClient EPG on dynamically allocated source ports used by WebClient when initiating the connection. This combination ensures that clients can initiate an HTTP request and receive responses from servers. References: = Implementing Cisco Application Centric Infrastructure Official Cert Guide

In the Cisco ACI fabric, to ensure that the IP address of Server S1 is learned and the IP addresses of BC1 and BC2 are not learned, one must limit IP learning to a specific subnet and suppress ARP responses from BC1 and BC2. By checking the “Limit IP learning to subnet” box (Option A), it ensures that only IPs within a defined subnet are learned, which would include Server S1’s IP but exclude BC1 and BC2 if they are outside of this subnet.Suppressing ARP response on BC1 and BC2 (Option D) prevents these devices from responding to ARP requests, which in turn prevents their IPs from being learned by other devices in the network. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

The protocol used for exchanging MAC/IP address information for endpoints between spine switches in different pods within a Cisco Multi-Pod solution is MP-BGPEVPN (Multiprotocol BGP Ethernet VPN). This protocol facilitates scalable communication between separate locations by allowing MAC/IP address information sharing across pods. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

An application-centric design in Cisco ACI focuses on the application requirements and interactions between different application components. In this design, EPGs (Endpoint Groups) represent different application tiers, such as web, application, and database tiers. This approach allows for a more flexible and scalable network configuration that aligns with the application architecture, enabling policies to be applied based on the application’s needs rather than the network topology. References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

Using an application-centric approach in Cisco ACI means that multiple VLANs and/or multiple EPGs can be grouped under one bridge domain. This approach aligns network constructs with application requirements, enabling more efficient and flexible network configurations.

References := Network Centric to ACI Centric Migration - Cisco

Within Cisco ACI, when a Topology Change Notification (TCN) BPDU is received in a VLAN, the system flushes the endpoints for the associated encapsulation to ensure network stability. Additionally, BPDU filter and BPDU guard can be configured on Cisco ACI leaf edge ports to protect against potential STP issues2.

 The output shows details of tunnel 6 within a Cisco ACI fabric. The transport protocol is listed as “isvlan,” which is typically associated with the GRE protocol in Cisco ACIterminology. GRE, a tunneling protocol developed by Cisco, encapsulates various network layer protocols inside virtual point-to-point links over an IP internetwork. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

When traffic to certain endpoints is dropped in a Cisco ACI fabric configured with hardware proxy, setting the L2 Unknown Unicast option to Flood for Layer 2 switched traffic can prevent this problem. This mode allows unknown unicast traffic to be flooded within the bridge domain, rather than being sent to the spine proxy and potentially discarded if the destination is unknown5.

References := Solved: Unknown Unicast in ACI Fabric - Cisco Community

 To advertise the 172.16.2.0/24 network learned from L3Out OSPF out of the fabric via EBGP, a subnet must be created within the L3Out’s External EPG and marked as “Shared Route Control Subnet.” This setting allows the route to be advertised to external routers through EBGP.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

 Migrating from Cisco NX-OS VXLAN to Cisco ACI fabric involves several considerations to minimize impact on workloads. Disabling bridge domain unicast routing while the default gateway remains in the VXLAN infrastructure ensures that the migration does not disrupt the existing traffic flow. This approach allows for a smoother transition by maintaining the current routing paths until the migration is complete123.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

In a Cisco ACI Multi-Site deployment, proper configuration of the inter-site link is crucial for traffic to pass between different sites. The MTU size is particularly important; if it’s not set correctly, packets may be dropped or fragmented, leading to connectivity issues. By configuring the MTU on the link to be at least 100 bytes larger than that of the ACI fabrics, you allow for encapsulation overhead without packet drops due to exceeding MTU limits. Additionally, configuring the link as a routed subinterface using VLAN-4 is necessary for routing across different broadcast domains, which is essential for inter-site communication in an ACI fabric. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide