Pass the Nokia SRC 4A0-100 Questions and answers with ValidTests

In the diagram:

R2 and R4 areboth within AS 65540, which indicates that they are in thesame Autonomous System.

eBGP (External Border Gateway Protocol)is designed for routingbetween different ASes(inter-AS routing).

Since R2 and R4 are in thesame AS, you would use:

OSPForIS-IS(both interior gateway protocols – IGPs)✔

Static routingis also valid between any two routers if manually configured✔

eBGP❌is invalid between routersin the same AS.

➡The correct protocol in that case would beiBGP (internal BGP)if BGP were to be used within the AS.

Therefore, the correct answer is: D. eBGP

A/31 subnetin IPv4 provides exactlytwo IP addresses(e.g., 192.168.1.0/31 → usable: 192.168.1.0 and 192.168.1.1). Traditionally, these would represent anetwork address and a broadcast address, butRFC 3021redefines /31 subnets forpoint-to-point links, such as router-to-router connections.

In a /31 subnet:

Broadcast address is not used.

Both IPs are treated as usable host addresses.

It'sideal for point-to-point links, saving address space.

This is widely supported andstandardized in Nokia IP and routing platforms.

Comprehensive and Detailed Explanation From Exact Extract:

In theNokia SR OS CLI, specifically in bothclassic CLIandMD-CLI, the"?" keyis used to display a list of all possible command options at a given point in the CLI, along with a brief description of each option.

This functionality helps the user in command discovery and reduces the chances of syntactical errors by showing only valid options.

The"Tab"key, while helpful, is primarily used forauto-completionand not for displaying detailed descriptions.

"Space bar"is used for command continuation, and"Return"executes the command or moves to the next line.

Correct usage example in classic CLI:

*A:SR1>config>router>interface# ?

- Shows all the valid commands and parameters under interface

TheNokia 7750 SR architectureseparates its operations intocontrol planeanddata planefunctions.

TheData Planeincludes hardware components responsible for forwarding traffic at line rate. These components include:

MDA (Media Dependent Adapter)– interfaces with physical media.

IOM (Input/Output Module)– performs high-speed packet forwarding and processing.

XMA (eXpandable Media Adapter)– extends port capacity and media support.

TheControl Planeincludes theCPM (Control Processor Module), which is responsible for running routing protocols, managing configuration, system operations, and other control-related functions. The CPM does not participate in data forwarding and is thusnot part of the data plane.

In Nokia SR OS, event logging allows the router to report system events, alarms, and operational changes to external systems or users. The valid logging destinations include:

SNMP– Used to send traps or informs to SNMP managers.

Syslog– Sends logs to centralized syslog servers, a standard for log management.

NETCONF– Can be used for event notification in model-driven management setups, although it is more frequently used for configuration and state management.

However,BOF (Boot Options File)isnota valid logging destination. TheBOFis used to store critical system boot configurations, such as:

Which image to boot from

Network interface settings

Auto-boot parameters

BOF plays no role in the logging infrastructure.

Ahubis aphysical layer (Layer 1)networking device used to connect multiple Ethernet devices in a network. Unlike switches or routers, hubs donot inspect or process frame headers. Instead, they perform a simple task:

Receive a signal (electrical or optical) on one port

Replicate that signal identically to all other ports

This means the hubdoes not examine Layer 2 (MAC addresses) or Layer 3 (IP addresses)and doesnot perform intelligent forwarding. It merelybroadcasts all incoming traffic to every other connected device, often resulting inhigh collision domainsand poor efficiency.

Option Adescribes arepeater, not a hub.

Option Cdescribes aswitch(Layer 2 device).

Option Ddescribes arouter(Layer 3 device).

Option Bis correct: A hub does not inspect headers and replicates traffic blindly.

TheShortest Path Tree (SPT)is calculated byLink-State routing protocolslikeOSPFandIS-ISusing:

Acomplete map of the network topology.

Each router uses algorithms likeDijkstra’sto compute the shortest paths to all destinations.

Option C is correct– fullnetwork topologyis used.

Option Arefers to Distance Vector methods.

Option BandDare results of topology analysis but not the input used.

Link-State routing protocols(e.g.,OSPF,IS-IS) operate by:

Each routerflooding link-state advertisements (LSAs)throughout the network.

Every router constructs acomplete map of the network topology.

Then each router runs theSPF algorithmto compute optimal paths.

Option C is correct– routers know theentire network topology.

Option A isDistance Vector behavior(e.g., RIP).

Option B isnot efficient or accurate for Link-State.

Option D –hop-countis used inDistance Vector(e.g., RIP).

Route summarization (a.k.a. supernetting)is the process ofcombining multiple contiguous subnetsinto asingle summarized route, which:

Reduces routing table entries

Enhances scalability and efficiency

Minimizes instability by localizing route changes

Option A is falsebecauseit describes subnetting, not summarization. Summarization works in theopposite direction– combining smaller routes into a larger one.

BGP (Border Gateway Protocol)uses amulti-step decision processto select the best route among multiple paths. It doesnot use SPF or simple metrics like hop count.

Key BGP selection criteria include:

Local preference

AS path length

Origin type

MED (Multi-Exit Discriminator)

eBGP over iBGP

IGP metric to next hop

Option C is correct– BGP evaluatesmultiple attributesfor route selection.