Nokia IP Networks and Services Fundamentals 4A0-100 Exam Questions

Answer : A

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 : A

Address summarization (also called route aggregation) is a technique used in IP routing to combine several contiguous network prefixes into a single summarized route.

This reduces the number of routes that need to be advertised and stored in routing tables, improving scalability and performance.

Option A is correct -- summarization replaces many specific routes with a single aggregated route.

Option B refers to best path selection (not summarization).

Option C is incorrect; duplicate advertisements are still processed and filtered based on metrics.

Option D is unrelated to summarization; directly connected routes are always advertised unless specifically filtered.

Nokia IP Routing Study Guide -- Chapter: ''Route Aggregation and Scalability''

Cisco & Juniper Routing Principles -- Route Summarization Best Practices

Answer : D

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) is not a valid logging destination. The BOF is 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.

Nokia SR OS Fundamentals Guide -- Section: ''Event Logging''

Nokia SRA Study Guide -- Chapter: 'Logging and Event Monitoring'

Answer : A

The Ingress Label Edge Router (LER) is the first router that:

Receives an unlabeled IP packet.

Applies an MPLS label based on its forwarding decision.

Forwards it into the MPLS core.

Option A is correct -- Ingress LER does MPLS label push.

Option B (Egress LER) -- removes labels at the end of the path.

Option C (LSR) -- switches labels, but doesn't push them onto unlabeled packets.

Option D -- is not a specific MPLS role.

Nokia IP/MPLS Fundamentals Guide -- Label Operations

RFC 3031 -- MPLS Architecture

Answer : B

When a router forwards a packet, it performs the following operations:

Looks up the destination IP address in the routing table to determine the next hop or egress interface.

Uses the ARP table to resolve the MAC address of the next-hop IP.

Option A is incorrect -- source IP is not used for route lookup.

Option C is incorrect -- routers don't resolve the source MAC.

Option D is partially true, but routing begins with the routing table, making B the most accurate.

Nokia IP Fundamentals Study Guide -- Chapter: ''IP Packet Forwarding''

RFC 1812 -- Requirements for IP Routers

Answer : B

A hub is a physical layer (Layer 1) networking device used to connect multiple Ethernet devices in a network. Unlike switches or routers, hubs do not 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 hub does not examine Layer 2 (MAC addresses) or Layer 3 (IP addresses) and does not perform intelligent forwarding. It merely broadcasts all incoming traffic to every other connected device, often resulting in high collision domains and poor efficiency.

Option A describes a repeater, not a hub.

Option C describes a switch (Layer 2 device).

Option D describes a router (Layer 3 device).

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

Nokia IP Networking Fundamentals Study Guide -- Chapter: 'Network Devices and OSI Model'

CompTIA Network+ and Cisco CCNA foundational guides (for universally accepted hardware behavior)

Answer : A

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'