Free D-SNC-DY-00 sample questions

Correct answer: Symmetric IRB using Type-5 routes

Symmetric IRB is designed for optimal East-West routing by performing routing at both ingress and egress VTEPs. This is achieved by using a dedicated L3 VNI for inter-subnet traffic and advertising IP prefixes using BGP EVPN Type-5 (IP Prefix) routes. This model avoids forcing all routed traffic through a centralized gateway or specific border leafs.

Correct answers: Priority-based Flow Control (PFC); Explicit Congestion Notification (ECN)

RoCEv2 (RDMA over Converged Ethernet) requires a lossless network fabric. This is achieved in SONiC by implementing Priority-based Flow Control (PFC) to prevent packet loss due to buffer exhaustion by sending pause frames on specific traffic classes, and Explicit Congestion Notification (ECN) to mark packets to signal congestion before it leads to drops, allowing endpoints to adjust their sending rates.

Correct answer: Consult the official Dell Technologies Enterprise SONiC User Guide for the specific hardware platform.

Port breakout capabilities are hardware-dependent and vary between different switch models and even ASICs. The definitive source for supported breakout modes, speeds, and configuration specifics is the official Dell Technologies documentation, specifically the Enterprise SONiC User Guide for that particular PowerSwitch model.

Correct answer: An ACL to match the traffic, a route-map to set the next-hop, and application of the route-map to the ingress interface.

The correct procedure for configuring PBR in SONiC (and most network operating systems) is to first define the interesting traffic using an Access Control List (ACL). Then, a route-map is created that matches this ACL and sets the desired action (e.g., `set ip next-hop 10.1.1.1`). Finally, this route-map policy is applied to the ingress interface where the traffic is expected to arrive.

Correct answer: ZTP with DHCP Option 239 (ZTP JSON file path)

SONiC's Zero Touch Provisioning (ZTP) feature is designed for this purpose. When a switch boots, it sends a DHCP request. The DHCP server must be configured to provide DHCP Option 239, which contains the URL pointing to the ZTP JSON provisioning file. This file instructs the switch on what configuration to download and apply.

Correct answer: False

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.

Correct answer: There is a Layer 3 connectivity issue, and the TCP three-way handshake cannot be completed.

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.

Correct answer: The core-facing port is not configured as a trunk port allowing S-VLAN 500.

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.

Correct answer: The specific hardware platform (ASIC) it is designed for.

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.

Correct answer: BGP EVPN Type-3 (Inclusive Multicast Ethernet Tag) routes are automatically generated and advertised by each VTEP.

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.