Important Nokia 4A0-100 Exam Questions

Answer: C

Explanation:

A P router (Provider router) is located in the core of the service provider's network. Its functions include:

Forwarding MPLS-labeled packets between PE routers.

Not interacting directly with customer routes or routing instances.

Having no knowledge of VPN routing or customer-specific services.

Option C is correct -- P routers sit in the MPLS core, isolated from customer edge.

Nokia MPLS and Services Guide -- Core vs Edge Router Roles

Nokia SRA Study Guide -- 'PE and P Devices in MPLS'

Answer: A

Explanation:

A broadcast domain is 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 to hubs.

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

Hubs are then connected to switches.

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 is a single Layer 2 broadcast domain.

There are no routers or VLANs to break or separate the domain.

Correct answer: A. 1

Nokia IP Networking Fundamentals Study Guide -- Chapter: 'LAN Switching and Broadcast Domains'

Cisco and CompTIA Network+ materials on 'Hubs vs Switches vs Routers in Broadcast Domains'

Answer: A

Explanation:

The DHCP client/server exchange follows a specific four-step sequence known as DORA:

Discover -- Client broadcasts to find available DHCP servers.

Offer -- DHCP server responds with an IP address offer.

Request -- Client requests the offered IP.

Acknowledgement -- Server confirms the lease.

This ensures dynamic IP configuration and is used in enterprise and home networks.

Nokia IP Fundamentals Guide -- DHCP Protocol Operation

RFC 2131 -- Dynamic Host Configuration Protocol

Answer: D

Explanation:

A MAC address (Media Access Control address) is a 48-bit identifier typically expressed in six groups of two hexadecimal digits (e.g., 00-20-60-CE-2B-28). It consists of two key parts:

OUI (Organizationally Unique Identifier) -- The first 24 bits (or first 3 octets, e.g., 00-20-60) are assigned by the IEEE to hardware manufacturers. This identifies the vendor or manufacturer.

Device Identifier (NIC Specific) -- The remaining 24 bits (e.g., CE-2B-28) are assigned uniquely by the vendor to each device/interface.

So in the address 00-20-60-CE-2B-28:

00-20-60 is the OUI

CE-2B-28 is the device-specific portion

Thus, the correct answer is D. 00-20-60.

IEEE MAC Address Standard (IEEE 802)

Nokia IP Networking Fundamentals Study Guide -- Chapter: 'Ethernet Addressing'

Answer: B

Explanation:

Spanning Tree Protocol (STP) is used specifically in Ethernet Layer 2 networks to prevent loops caused by redundant paths.

STP detects loops and blocks one or more redundant paths to ensure there is a loop-free topology in a bridged network.

STP dynamically recalculates the topology if a link fails, reactivating previously blocked paths.

Explanation of other options:

A . MPLS with LSPs: MPLS uses its own mechanisms for path management, such as RSVP or Segment Routing. STP is not applicable here.

C . OSPF with ECMP (Equal-Cost Multi-Path): OSPF is a Layer 3 protocol that inherently supports multiple paths without loops; STP is not involved.

D . eBGP (Exterior Border Gateway Protocol): Operates at Layer 3 for inter-AS communication; STP is not used in BGP routing.

Therefore, Option B is correct, as STP is explicitly designed for Layer 2 Ethernet networks with redundant paths.

Nokia IP Networking Fundamentals Study Guide -- Chapter: 'Layer 2 Technologies'

IEEE 802.1D Standard -- Spanning Tree Protocol Overview