D-SNC-DY-00 Sample Questions

D-SNC-DY-00 Sample Questions & Answers

Port groups, profiles, and management access make up the largest block, from ONIE-based installs and bundle selection to static and OSPF routing, VXLAN with Asymmetric IRB and BGP EVPN, and QoS features.

Launch the full D-SNC-DY-00 simulator →

Showing 10 of 20 free samples.

  1. Question 1Beginner

    SONiC Configuration · Configure and verify MC-LAG

    True or False: In an Enterprise SONiC MC-LAG deployment, the keep-alive link is mandatory and is actively used for forwarding data plane traffic between the two peer switches.

    Show answer & explanation

    Correct answer: B

    This statement is false. The keep-alive link is a mandatory control plane link used for heartbeat messages to detect peer availability and prevent split-brain scenarios. The peer-link is the high-bandwidth link used for synchronizing state and forwarding data plane traffic between the MC-LAG peers.

  2. Question 2Intermediate

    Routing · Configure and verify BGP

    A network engineer is configuring a BGP session between two Dell SONiC switches in different Autonomous Systems (AS 65001 and AS 65002). After configuring the neighbor relationship, the BGP session is stuck in the 'Active' state. What is the most common reason for a BGP session to remain in the Active state?

    Show answer & explanation

    Correct answer: C

    The BGP 'Active' state indicates that the local router is actively trying to establish a TCP connection (on port 179) with its peer but is failing. This is almost always due to a Layer 3 reachability problem, such as an incorrect IP address, a missing route to the peer, or a firewall blocking TCP port 179. A mismatched AS number would result in an 'OpenConfirm' failure, not a stuck 'Active' state.

  3. Question 3Intermediate

    SONiC Configuration · Configure and verify Q-in-Q tunnel configuration

    A service provider is using Q-in-Q tunneling to transparently carry customer VLAN traffic across its network. A customer reports that traffic for their VLAN 100 is not passing. The provider's core network uses Service-VLAN (S-VLAN) 500 for this customer. What is the most likely configuration error on the provider edge switch running SONiC?

    Show answer & explanation

    Correct answer: B

    For Q-in-Q to work, the customer-facing port must be configured to accept the customer's tagged traffic and map it to an S-VLAN. Crucially, the port facing the provider's core network must be configured as a standard 802.1Q trunk that explicitly allows the S-VLAN (in this case, 500) to pass. If S-VLAN 500 is not permitted on the core-facing trunk, the doubly-tagged frames will be dropped.

  4. Question 4Beginner

    SONiC Bundles · Compare Enterprise SONiC bundles

    When comparing different Enterprise SONiC bundles provided by Dell Technologies, what is the primary factor that differentiates one bundle from another?

    Show answer & explanation

    Correct answer: B

    Enterprise SONiC bundles are specifically compiled and packaged for different hardware platforms and their underlying ASICs (e.g., Broadcom, Mellanox). The bundle contains the platform-specific drivers, daemons, and software development kits (SDKs) necessary for the NOS to interact with the hardware. Therefore, the primary differentiator is the target hardware platform.

  5. Question 5Advanced

    VXLAN · Configure and verify BGP EVPN with Asymmetric IRB

    In a VXLAN fabric, a VTEP needs to send a BUM (Broadcast, Unknown Unicast, Multicast) frame to all other VTEPs participating in the same VNI. In a BGP EVPN deployment, which mechanism is used to discover the list of remote VTEPs for replicating BUM traffic?

    Show answer & explanation

    Correct answer: C

    BGP EVPN uses ingress replication for BUM traffic handling. To achieve this, each VTEP advertises a Type-3 (Inclusive Multicast Ethernet Tag) route. This route contains the VTEP's own IP address. All other VTEPs in the same VNI receive these Type-3 routes and use them to build a list of remote VTEP IP addresses to which they must replicate BUM traffic.

  6. Question 6Intermediate

    SONiC Configuration · Configure and verify VRRP

    A network administrator has configured two Dell SONiC switches (SW1 and SW2) for VRRP. SW1 is configured with priority 110 and preemption enabled. SW2 is configured with the default priority. Initially, SW1 becomes the master. If SW1 fails and SW2 takes over as master, what will happen when SW1 recovers and comes back online?

    Show answer & explanation

    Correct answer: B

    The VRRP default priority is 100. Since SW1 has a higher priority (110) and preemption is explicitly enabled, it has the right to take over the master role from a lower-priority router. When SW1 comes back online, it will see that the current master (SW2) has a lower priority (100) and will preempt it to become the master.

  7. Question 7Advanced

    VXLAN · Configure and verify BGP EVPN with Symmetric IRB

    Case Study

    A financial services company is modernizing its data center network using Dell PowerSwitch hardware running Enterprise SONiC. The new design is a leaf-spine fabric that must support both existing bare-metal servers and a new containerized application platform. The company has strict requirements for network segmentation, performance, and operational scalability.

    Current Situation:
    The existing network is a traditional three-tier architecture with significant reliance on Spanning Tree Protocol (STP) and manual VLAN provisioning. The bare-metal servers host legacy applications that require Layer 2 adjacency within their respective server pods. The new container platform requires a highly scalable Layer 3 fabric with robust multi-tenancy and the ability to rapidly provision and tear down isolated network segments.

    Requirements:

    1. Eliminate STP from the fabric core.
    2. Provide Layer 2 adjacency for legacy applications within each leaf-pair/pod.
    3. Implement a scalable, standards-based overlay network for the container platform.
    4. Ensure optimal East-West traffic routing for inter-application communication.
    5. The solution must use a control plane for MAC and IP address learning to avoid flood-and-learn behavior in the overlay.

    Proposed Solution:
    The network team plans to use MC-LAG at the leaf layer for server connectivity and a VXLAN BGP EVPN overlay for the fabric. They are debating between Asymmetric and Symmetric IRB models for routing between different network segments (VNIs). Given the requirement for optimal East-West traffic routing at scale, which approach is the most appropriate for the overlay network?

    Show answer & explanation

    Correct answer: D

    The Symmetric IRB model is the superior choice for this scenario. It directly addresses the requirement for optimal East-West routing at scale by distributing the routing function across all VTEPs. It uses a dedicated L3 VNI and BGP EVPN Type-5 routes to advertise IP prefixes, allowing any leaf to route traffic directly to the destination leaf without hair-pinning. This aligns perfectly with the needs of a modern, scalable container platform while BGP EVPN provides the control plane for MAC/IP learning.

  8. Question 8Beginner

    Routing · Configure and verify a single area OSPF topology

    Which command is used within the FRRouting (vtysh) shell on a SONiC switch to verify OSPF neighbor adjacencies and their current state?

    Show answer & explanation

    Correct answer: C

    The show ip ospf neighbor command is the standard FRRouting command used to display a list of all OSPF neighbors, their priority, state (e.g., Full/DR, Full/BDR, 2-Way), dead time, and the interface on which they were discovered.

  9. Question 9Intermediate

    QoS · Configure and verify QoS features

    An administrator needs to configure a QoS policy that maps incoming traffic with a DSCP value of 46 (EF - Expedited Forwarding) to a high-priority queue. Which SONiC configuration object is used to create this mapping between a DSCP value and an internal traffic class?

    Show answer & explanation

    Correct answer: C

    In SONiC, QoS Maps are used to translate traffic markings into internal classifications. Specifically, a DSCP_TO_TC_MAP (Differentiated Services Code Point to Traffic Class Map) is defined to map specific incoming DSCP values to internal Traffic Class (TC) numbers. This TC is then mapped to a specific hardware queue.

  10. Question 10Intermediate

    SONiC Configuration · Configure and verify MC-LAG

    A consultant is reviewing an MC-LAG configuration between two Dell SONiC switches. They notice that the system-mac address is configured identically on both peers. What is the primary purpose of this configuration?

    Show answer & explanation

    Correct answer: B

    The LACP protocol uses a system ID, which is derived from the switch's system MAC address, to identify a unique LACP-speaking device. By configuring the same system-mac on both MC-LAG peers, they present an identical system ID to any downstream device (like a server). This makes the downstream device believe it is connected to a single logical switch, allowing it to form a standard LACP port-channel across the two physical switches.

Ready for the real thing?

The full D-SNC-DY-00 simulator has every exam-style question, timed mode, and instant scoring.

Go to the D-SNC-DY-00 simulator →