4A0-D01 Nokia Data Center Fabric Fundamentals Exam Questions and Answers

Comprehensive and Detailed Explanation From Exact Extract:

Option A: TRUE – "duplicate" status confirms multiple interfaces.

"A 'duplicate' entry indicates the MAC was detected on multiple ports."

— SR Linux Bridge Table Guide, "Duplicate MAC Handling"

Option B: FALSE – No re-learning rate data is present. The output shows a static duplicate entry, not rate violations.

"MAC re-learning rate thresholds generate specific alerts (not shown here). This exhibit only shows a persistent duplicate state."

— SR Linux Monitoring Guide, "MAC Mobility Events"

Option C: TRUE – The MAC is explicitly bound to ethernet-1/10.0.

"The 'Destination' column specifies the interface where the MAC was last observed."

— SR Linux CLI Reference, "show bridge-table"

Option D: TRUE – Duplicate detection is active since duplicates are flagged.

"The presence of 'duplicate' entries confirms MAC duplication detection is enabled."

— SR Linux Security Guide, "MAC Duplication"

Conclusion: Option B is unsupported by the exhibit.

Comprehensive and Detailed Explanation with Exact Extracts:

Options A, B, and C are TRUE:

A: BFD detects microsecond-level link failures, faster than BGP timers.

B: BFD negotiates a control-packet rate during session setup.

C: Missed BFD packets trigger a session-down event, notifying BGP.

Extract from Nokia SR Linux Configuration Guide (Section: BFD for BGP):

"BFD provides sub-second failure detection. Peers negotiate tx-interval and rx-interval timers dynamically. If the configured multiplier threshold of missed packets is reached, BFD notifies BGP to tear down the session."

Option D is FALSE: BFD does not modify BGP’s update timers (e.g., min-advertisement-interval). It only accelerates failure detection.

Extract from Nokia SR Linux Fundamentals Guide (Section: BFD Integration):

"BFD does not influence BGP’s route advertisement or withdrawal timers. It solely enhances failure detection speed, allowing BGP to react faster to topology changes."

Comprehensive and Detailed Explanation with Exact Extracts:

Options A, B, and C are Day 2+ operations:

A: Telemetry enables real-time monitoring.

B: Health analysis supports proactive maintenance.

C: Sandbox validates changes pre-deployment.

Extract from Nokia FSS Day 2 Operations Guide:

"Day 2+ includes telemetry-based monitoring, health analytics, and sandbox testing for upgrades/changes."

Option D is a Day 0 activity:

Fabric intents define initial design templates (Day 0), not ongoing operations.

Extract from Nokia FSS Lifecycle Management Guide:

"Fabric intents are used during Day 0 design to build templates. Day 2+ focuses on operational tasks like monitoring (A), health checks (B), and sandbox validation (C)."

Comprehensive and Detailed Explanation From Exact Extract:

Option A: TRUE – SR Linux leverages an unmodified Linux kernel for broad third-party compatibility.

"SR Linux uses a standard, unmodified Linux kernel, enabling seamless integration of third-party applications."

— Nokia SR Linux Technical Overview, "Linux Foundation"

Option B: TRUE – Its state-driven architecture (centered on the Interface Database) enables efficient data access.

"The state-driven architecture provides applications with granular, real-time access to system state via the IDB."

— SR Linux Architecture White Paper, "State-Driven Design"

Option C: TRUE – The NetOps Development Kit (NDK) (not "NetOgs") supports third-party app integration.

"The NetOps Development Kit (NDK) offers tools and libraries for third-party application development and integration."

— SR Linux DevOps Guide, "NDK Overview"

Option D: FALSE – SNMP is not used for CLI access. SR Linux uses gNMI, JSON-RPC, or SSH/CLI.

"SR Linux CLI is accessed via SSH or modern interfaces (gNMI/JSON-RPC). SNMP is supported only for legacy monitoring, not CLI interaction."

— SR Linux Management Interfaces Guide, "Protocol Support"

Conclusion: Option D is incorrect as SNMP is not a CLI access method.

Comprehensive and Detailed Explanation From Exact Extract:

Option A: TRUE – IP addresses are assigned to IRB subinterfaces.

"The IRB subinterface configuration includes the IP address for integrated routing."

— SR Linux EVPN Guide, "IRB Configuration"

Option B: TRUE – IRB subinterfaces reside in IP-VRF instances.

"IRB subinterfaces are associated with an IP-VRF network instance for L3 routing."

— SR Linux Network Instance Guide, "IP-VRF Setup"

Option C: FALSE – One IRB subinterface serves an entire MAC-VRF (L2 domain), not per interface.

"A single IRB subinterface provides L3 gateway services for all interfaces in a MAC-VRF instance."

— SR Linux EVPN Guide, "Asymmetric IRB Design"

Option D: TRUE – Each MAC-VRF uses one IRB subinterface.

"Each MAC-VRF network instance requires exactly one IRB subinterface for inter-subnet routing."

— SR Linux Network Instance Guide, "MAC-VRF Integration"

Comprehensive and Detailed Explanation with Exact Extracts:

Option B (CPM-filter ACL) is CORRECT:

The CPM-filter ACL is explicitly designed to match control-plane traffic and copy it to the CPM (Control/Management Plane). It is instantiated in hardware on all line cards.

Extract from Nokia SR Linux Security Guide (Section: Control Plane Protection):

"The cpm-filter ACL is instantiated on every line card to identify packets destined for the CPM (e.g., routing protocols, ICMP). Matched packets are copied to the CPM while data-plane traffic is forwarded normally."

Other Options are INCORRECT:

A: Capture-filter ACL is for packet mirroring (e.g., SPAN), not CPM copying.

C/D: Ingress/Egress ACLs filter user traffic and are not specific to CPM-bound packets.

Extract from Nokia SR Linux ACL Configuration Guide:

"Only cpm-filter ACLs are globally applied across line cards for CPM protection. Interface ACLs (ingress/egress) operate locally and do not copy packets to the CPM."

Comprehensive and Detailed Explanation:

Nokia’s Fabric Services System (FSS) employs an intent-driven approach where the fabric intent is defined in a YAML file. This file specifies the desired state of the data center fabric, including topology, services, and policies. FSS translates this declarative intent into device-specific configurations.

Exact Extract:

"Fabric Services System uses intent-based YAML templates to define the fabric’s target state. The system automates configuration generation and deployment, ensuring consistency across the fabric."