Nokia Certification 4A0-D01 Updated Exam

Comprehensive and Detailed Explanation with Exact Extracts:

Options A, B, and C are part of ZTP autoboot:

A: DHCP assigns IP/gateway.

B/C: Scripts download images/RPMs from servers (HTTP/FTP).

Extract from Nokia SR Linux ZTP Guide:

"Autoboot triggers DHCP discovery for IP/gateway. The device then fetches a provisioning script (via DHCP/DNS) that downloads RPMs/images from HTTP/FTP servers."

Option D is NOT part of ZTP autoboot:

Fabric Services System (FSS) and its digital sandbox are separate tools for lifecycle management. ZTP does not auto-deploy them.

Extract from Nokia FSS Deployment Guide:

"FSS deployment requires manual setup or orchestration tools. The digital sandbox is not automatically deployed via ZTP autoboot."

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 – 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 A & B are FALSE: While recursive lookups are required for both next-hops (10.1.1.0 and 10.2.1.0), there is no dependency between them. Each next-hop must be resolved independently via a separate recursive lookup in the routing table. Neither next-hop is resolved "using" the other.

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

"An indirect next-hop is not directly connected. The system must perform a recursive lookup in the routing table to find a route that matches the indirect next-hop IP address and resolve it to a directly attached next-hop and egress interface. Each indirect next-hop in a route is resolved independently."

Extract from Nokia SR Linux Fundamentals Guide (Section: Route Resolution):

"Routes with indirect next-hops require recursive route lookup. The router searches its routing table for a path to the indirect next-hop IP address itself. Multiple indirect next-hops in a single route entry are resolved in parallel, not sequentially."

Option C is TRUE: The exhibit shows a single static route (192.168.20.0/30) with two indirect next-hops (10.1.1.0 and 10.2.1.0). This configuration defines a next-hop group with two members for this route, enabling Equal-Cost Multi-Path (ECMP) load balancing or redundancy.

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

"Multiple next-hop addresses can be specified for a static route. This creates a next-hop group. Traffic matching the route prefix is load-balanced across all active next-hops in the group using ECMP."

Extract from Nokia SR Linux Fundamentals Guide (Section: Static Routing):

"A static route entry listing multiple next-hops implies a next-hop group. The number of next-hops listed in the show route-table output for a single route ID directly indicates the number of next-hops configured in the group."

Option D is FALSE: The preference value (Pref) is configured per route, not per next-hop within the route. Both next-hops (10.1.1.0 and 10.2.1.0) share the same preference value (5), as they belong to the same route entry (ID 0). Next-hop selection within the group is based on the ECMP hashing algorithm, not preference. Preference is used to choose between different routes (from different protocols) to the same prefix.

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

"The preference value is a property of the static route itself, not individual next-hops within it. All next-hops in a static route's next-hop group inherit the same preference value."

Extract from Nokia SR Linux Fundamentals Guide (Section: Route Selection):

"When multiple next-hops exist for a route (ECMP), the active next-hop for a specific flow is determined by a hash of packet header fields (e.g., 5-tuple). Preference values are only compared when selecting between different routes (e.g., static vs. BGP) to the same prefix."