Nokia 4A0-100 Dumps

In a typical MPLS/VPN service architecture:

PE (Provider Edge) router: Directly connects to thecustomer edge (CE)device.

P (Provider) router: Only forwards MPLS-labeled packets, doesnot touch customer routes.

LSR (Label Switch Router): General term, can be either PE or P depending on placement.

Correct Answer: A – PE

Itinterfaces with CE devicesandruns customer routing protocols(e.g., OSPF, BGP).

OSPF (Open Shortest Path First)is aLink-State protocolthat uses:

Cost (based on bandwidth)as its metric.

Dijkstra’s algorithmto compute shortest path trees.

Supportshierarchical routing with areas(e.g., Area 0 as backbone).

Routers exchangeLSAs, not full routing tables.

Option D is FALSE– OSPF doesnot use hop-count. That’s aRIP (Distance Vector)feature.

AVPRN (Virtual Private Routed Network)provides aLayer 3 VPN serviceover a service provider’s network.

Each customer site connects to aPE router.

Sites are connected via arouted networkusingseparate routing instances.

Customer routers seerouted connectivity, as if connected to their own private WAN.

Option C is correct– VPRN providesrouted connectivitybetween sites.

Abroadcast domainis a logical division of a network in which all nodes can reach each other with broadcast frames (Layer 2). Devices within the same broadcast domain receive broadcast packets sent by others.

In the diagram:

Multiple users connect tohubs.

Hubs are Layer 1 devices anddo not break broadcast domains. They simply replicate incoming electrical signals to all ports.

Hubs are then connected toswitches.

Switches, unless VLANs are configured,forward broadcasts to all ports except the incoming one, effectively keeping all devices in the same broadcast domain.

The two switches are connected together without VLAN segmentation.

Therefore:

The entire LAN depicted isa single Layer 2 broadcast domain.

There areno routers or VLANsto break or separate the domain.

Correct answer: A. 1

On theNokia 7750 SR, theControl Processor Module (CPM)includes two compact flash slots,CF1 and CF2, which are used for storing crucial system files. These include:

Runtime software image

Configuration files

Logs and backup configurations

BothCF1 and CF2are used for redundancy and flexibility. Typically, CF1 is designated as the primary storage location for the active software image and configuration, while CF2 serves as a backup. In some configurations, the router can boot from either CF1 or CF2 depending on system settings and availability.

This redundancy is essential for high availability and fast recovery in the event of a failure or manual software update.

In MPLS architecture, theIngress LER (Label Edge Router)is responsible for:

Pushing labelsonto unlabeled packets and injecting them into the MPLS domain.

Acting as thestarting point of the Label Switched Path (LSP).

From the diagram:

R1is thestarting point (Ingress LER)for both LSP A and LSP B.

R4is theEgress LER, which wouldpopthe labels at the end of the LSP.

So,R1 is responsible for label push (imposing)at the start of both LSPs.

Option A is correct– R1 pushes labels for both LSP A and LSP B.

Option Bis incorrect – R4 is an egress router, not ingress.

Option C/Dare incorrect – the LSPs both start at R1.

Astatic routeis a manually configured route added by a network administrator. It does not rely on dynamic routing protocols or metrics.

Itdoes not exchangeroutes with other routers (A – false).

It can be used bothwithin or across ASes(B – false).

Itdoes not use metricslike hop count (C – false).

Option D is correct– the operator explicitly defines the next-hop IP or egress interface manually.

Static routes are often used for:

Default routing

Backup routing

Simple or small networks

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.

A Virtual Private Network (VPN) is designed to provide secure and private communication over a shared or public infrastructure. Key characteristics of VPNs include:​

Traffic Isolation:Each customer's traffic is kept separate from others, ensuring privacy and security.​

Shared Infrastructure:Service providers can support multiple VPNs over the same physical infrastructure, optimizing resource utilization.​

Customization:VPNs can be tailored to meet the specific requirements of individual customers, including security policies, routing, and quality of service.​

However,customer data is not alteredas it traverses a VPN. Instead, VPNs employ encryption and tunneling protocols to protect data integrity and confidentiality during transmission. The primary goal is to ensure that data remains unchanged and secure from end to end.​

The Link layer, also known as the Data Link layer in the OSI model, is responsible for encapsulating packets from the Network layer into frames suitable for transmission over the physical medium. This process includes adding headers and trailers to the packet to create a frame, which contains necessary information for error detection, addressing, and control.​

According to the OSI model, the Data Link layer serves as the intermediary between the Network layer and the Physical layer. It ensures that data is packaged into frames and manages the access to the physical transmission medium.​

Option A correctly describes this function.​

Option B pertains to the Network layer, which is responsible for encapsulating data into IP datagrams and determining the routing of these datagrams across networks.​

Option C relates to the Transport layer, which handles the encapsulation of application data into transport layer segments, such as TCP or UDP messages.​

Option D is a function of the Physical layer, which deals with the transmission and reception of raw bitstreams over a physical medium, including the timing and synchronization of signals.​

A layered protocol stack is designed to simplify network communication by separating functionalities into distinct layers. Each layer has a defined role and communicates with the layers directly above and below it. The main benefits of this model include:

Simplified design and implementation: Developers can focus on one layer without needing to understand the entire system.

Flexibility: New protocols can be developed and inserted at specific layers without redesigning the whole stack.

Interoperability: Standard interfaces allow different systems and vendors to work together.

Isolation of functions: Errors and updates can be managed within one layer without impacting others.

However,reducing protocol overhead is not a primary goalof this model. In fact, the encapsulation and interaction between layers can sometimesintroduce extra overhead. This overhead is a trade-off accepted to gain the other benefits listed above.

AVirtual Local Area Network (VLAN)is a logical separation of devices atLayer 2, even ifthose devices are connected to the same physical switch. Each VLAN forms itsown broadcast domain, and traffic cannot cross from one VLAN to anotherwithout Layer 3 routing.

Option Ais incorrect – devices on the same switch but in different VLANs still cannot communicate directly.

Option Bis incorrect – VLANs explicitlycreate separate broadcast domains.

Option Dis technically incorrect – communication is possible with the right setup.

Option Cis correct – to enable communication between different VLANs, arouteror aLayer 3 switchwith inter-VLAN routing capability is required.

This process is calledinter-VLAN routing, and it's a fundamental task in enterprise networks using VLANs.