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

Comprehensive and Detailed Explanation with Exact Extracts:

Options A, B, and D are supported:

SR Linux users (A): Locally configured users for CLI/management access.

Regular Linux OS users (B): Native Linux users (e.g., admin) for host OS operations.

Remote users (D): Authenticated via AAA (TACACS+/RADIUS).

Extract from Nokia SR Linux System Management Guide:

"User types include SR Linux users (CLI access), Linux OS users (host system), and remote users (external AAA)."

Option C (Container users) is NOT supported:

SR Linux does not define "container users" as a distinct category. Containers (e.g., management container) share the host's user management.

Extract from Nokia SR Linux Security Guide:

"SR Linux does not provision separate user identities for containers. User access is managed at the host OS level or via SR Linux CLI, with no container-specific user type."

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:

Options A, B, and C ARE configured in static-routes:

Blackhole: Configured under static-routes for a prefix to drop traffic.

IPv4 destination prefix: Defined directly in the static-routes container.

Preference value: Set per static route entry within static-routes.

Extract from Nokia SR Linux Configuration Guide (Section: Static Routes):

"Static routes are configured under /routing-policy/static-routes. Each entry requires a prefix (e.g., 0.0.0.0/0). The blackhole parameter and preference value are configured directly within this container for a specific prefix."

Option D (Next-hop group) CANNOT be configured in static-routes:

Next-hop groups are separate objects defined under /routing-policy/next-hop-groups.

The static-routes container references a next-hop group by name but does not define its properties.

Extract from Nokia SR Linux Configuration Guide (Section: Next-Hop Groups):

"Next-hop groups are configured under /routing-policy/next-hop-groups. Each group is given a name and defines properties like next-hop IPs, blackhole behavior, or indirect settings. Static routes reference a next-hop group via the next-hop-group parameter under /routing-policy/static-routes but do not configure the group itself here."

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 with Exact Extracts:

Option B is FALSE:

The system-cpu-policer is a software-based policer running on the CPM CPU, not hardware-based.

Extract from Nokia SR Linux QoS Guide (Section: Control Plane Policing):

"The system-cpu-policer is enforced in software on the CPM. In contrast, distributed-policers are hardware-based and execute on line cards."

Other Options are TRUE:

A: Hierarchical policing (e.g., per-protocol child policers under an aggregate) is supported.

Extract: "Hierarchical policers allow aggregate rate-limiting plus per-protocol sub-policers (e.g., for BGP, OSPF)."

C: The system-cpu-policer polices the aggregate traffic reaching the CPM.

Extract: "system-cpu-policer applies to the sum of all traffic forwarded from line cards to the CPM."

D: CPM-filter entries can combine both policers:

distributed-policer (line card hardware) for early per-card rate-limiting.

system-cpu-policer (CPM software) for final aggregate policing.

Extract: "CPM-filter entries may reference both a distributed-policer (for per-line card enforcement) and a system-cpu-policer (for CPM-wide aggregation)."

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:

Option A is FALSE: The provisioning script URL is not defined in the TLS profile. It is provided via DHCP (option 239) or DNS.

Extract from Nokia SR Linux ZTP Guide:

"The DHCP server supplies the URL to the provisioning script (via option 239). TLS profiles secure script/image downloads but do not define the script location."

Options B, C, and D are TRUE:

B: ZTP is managed by the ztp application in the management container.

C: DHCP provides initial IP/gateway.

D: ZTP requires no manual configuration.

Extract from Nokia SR Linux Installation Guide:

"The ZTP application automates deployment. It uses DHCP for network parameters and fetches scripts to make the device operational without pre-configuration."