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

Comprehensive and Detailed Explanation From Exact Extract:

Option A: TRUE – Only one management interface (mgmt0) exists.

"The system supports a single management interface (mgmt0) for out-of-band access."

— SR Linux Interface Guide, "Management Port"

Option B: TRUE – Network interfaces bind to hardware ports.

"Network interfaces (e.g., ethernet-1/1) map directly to physical line card ports."

— SR Linux Interface Guide, "Port Mapping"

Option C: FALSE – Loopback interfaces are virtual, not physical.

"Loopback interfaces (e.g., lo0) are logical entities with no physical hardware association."

— SR Linux Routing Guide, "Loopback Interfaces"

Option D: TRUE – L2 parameters (e.g., MTU) are set at the main interface; L3 (e.g., IP) at subinterfaces.

"Layer 2 attributes (MTU, admin-state) are configured under the main interface. Layer 3 settings (IP, VRF) are applied to subinterfaces."

— SR Linux Interface Guide, "Subinterface Configuration"

Comprehensive and Detailed Explanation From Exact Extract:

Option A: TRUE – state mode shows configuration + operational state.

"The state command provides a unified view of configuration and real-time operational data."

— SR Linux CLI User Guide, "State Mode"

Option B: TRUE – show mode uses predefined templates.

"show commands use structured report templates for consistent operational data display."

— SR Linux CLI User Guide, "Show Commands"

Option C: TRUE – running mode is for configuration changes.

"Configuration edits occur in running mode, which modifies the candidate configuration."

— SR Linux Configuration Fundamentals, "CLI Modes"

Option D: FALSE – use (not enter) switches modes.

"Mode transitions use the use command (e.g., use state). enter navigates hierarchical paths within a mode."

— SR Linux CLI User Guide, "Mode Navigation"

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 From Exact Extract:

In a leaf-spine Clos network:

Option A is TRUE: Each leaf connects to every spine for full redundancy and non-blocking fabric.

"In a Clos topology, every leaf node connects to every spine node, ensuring any-to-any connectivity."

— Nokia Data Center Fabric Design Guide, "Leaf-Spine Architecture"

Option B is TRUE: East-west traffic flows predictably via spines.

"Leaf-spine provides deterministic paths for east-west traffic, minimizing latency and jitter."

— Nokia SR Linux EVPN Configuration Guide, "Traffic Flow in Clos Networks"

Option C is FALSE: Clos networks do not use STP. They rely on Layer 3 ECMP and routing protocols for loop avoidance.

"Clos fabrics eliminate STP by design. Forwarding loops are avoided through ECMP and routing protocols (e.g., BGP), not Layer 2 STP."

— Nokia Data Center Fabric Best Practices, "Loop Avoidance"

Option D is TRUE: ECMP load-balances traffic across multiple spine paths.

"ECMP is fundamental to leaf-spine, distributing traffic across all available spine links."

— Nokia SR Linux Routing Guide, "ECMP in Clos Fabrics"

Comprehensive and Detailed Explanation From Exact Extract:

Option A: FALSE – Checkpoint 0 is the latest (most recent), not the oldest.

"Checkpoints are numbered sequentially, with 0 representing the most recent checkpoint. Higher numbers indicate older checkpoints."

— SR Linux Configuration Management Guide, "Checkpoint Numbering"

Option B: TRUE – Checkpoints are stored as JSON files.

"Checkpoints capture the running configuration in JSON format for easy parsing and restoration."

— SR Linux CLI User Guide, "Checkpoint Operations"

Option C: TRUE – Reversion to any checkpoint is supported.

"Operators can revert to any saved checkpoint, restoring the system to that specific state."

— SR Linux Configuration Management Guide, "Checkpoint Revert"

Option D: TRUE – Checkpoints can be auto-generated on commit.

"The system can be configured to create a new checkpoint automatically upon successful commit."

— SR Linux CLI User Guide, "Commit Options"

Conclusion: Option A is false because checkpoint 0 is the newest.

Comprehensive and Detailed Explanation with Exact Extracts:

Option A (Valid): Log sources can be defined using Linux syslog facilities (e.g., local6) and priorities.

Extract from Nokia SR Linux Configuration Guide:

"Log sources are identified using Linux facilities (e.g., kernel, local6) and priorities (e.g., info, error)."

Option B (Valid): The console is a valid source for log messages (e.g., kernel boot logs).

Extract from Nokia SR Linux Fundamentals Guide:

"Console output is treated as a log source, particularly for kernel and early-boot messages captured before system services initialize."

Option C (Valid): SR Linux subsystems (e.g., bgp, system) generate logs with specific priorities.

Extract from Nokia SR Linux Configuration Guide (Section: Log Filters):

"Logs generated by SR Linux subsystems (e.g., network-instance, interface) can be filtered by subsystem name and priority."

Option D (Invalid): "Syslog filter" is not a source—it is a configuration mechanism.

Extract from Nokia SR Linux System Management Guide:

"Filters (/system logging filter) are applied to log sources (facilities/subsystems) to select messages for destinations. Filters themselves do not generate logs."

Comprehensive and Detailed Explanation From Exact Extract:

Option A: TRUE – IP-VRF is defined as a Layer 3 routing instance.

"An IP-VRF network instance provides Layer 3 routing services, isolating tenant routing domains."

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

Option B: TRUE – Forwarding decisions are IP-based.

"IP-VRF forwards packets based on destination IP address using its dedicated routing table."

— SR Linux Routing Guide, "IP-VRF Forwarding"

Option C: TRUE – Each IP-VRF has an independent route table.

"Each IP-VRF maintains a separate route table for complete routing isolation."

— SR Linux Configuration Guide, "Network Instances"

Option D: FALSE – Multiple servers in the same subnet belong to a MAC-VRF (L2 domain), not IP-VRF. IP-VRF handles inter-subnet routing.

"Servers in the same IP subnet must reside in the same MAC-VRF (Layer 2 bridge domain). The IP-VRF provides routing between subnets."

— *SR Linux EVPN Services Guide, "L2/L3 Integration"*

Conclusion: Option D is false because same-subnet devices are grouped in MAC-VRF.