The Nokia IP Networksand Services Fundamentals (4A0-100)

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.

The Internet Assigned Numbers Authority (IANA) is responsible for managing the global IP address pool , along with:

Allocating blocks of IP addresses to Regional Internet Registries (RIRs) such as ARIN (North America), RIPE NCC (Europe), APNIC (Asia-Pacific), etc.

Managing autonomous system numbers (ASNs) .

Overseeing DNS root zones and protocol parameters.

IANA does not assign IPs directly to enterprises or individuals — those tasks are delegated to RIRs and ISPs .

Option A & B: Enterprises and residential allocations are handled by ISPs or RIRs.

Option D: North American IPs are managed by ARIN , not IANA.

Option C is correct – IANA manages the global IP address allocation hierarchy.

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.​

BGP (Border Gateway Protocol) uses a multi-step decision process to select the best route among multiple paths. It does not 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 evaluates multiple attributes for route selection.

A Virtual Local Area Network (VLAN) is a logical separation of devices at Layer 2 , even if those devices are connected to the same physical switch. Each VLAN forms its own broadcast domain , and traffic cannot cross from one VLAN to another without Layer 3 routing .

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

Option B is incorrect – VLANs explicitly create separate broadcast domains .

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

Option C is correct – to enable communication between different VLANs, a router or a Layer 3 switch with inter-VLAN routing capability is required.

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

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.

On the Nokia 7750 SR , the Control 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

Both CF1 and CF2 are 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.

A /26 subnet means 26 bits for the network and 6 bits for host addressing (32 - 26 = 6):

2⁶ = 64 total addresses per subnet

64 - 2 = 62 usable host addresses per subnet

/24 to /26 increases subnet bits by 2 , so:

2² = 4 subnets from one /24

But the question asks about using /26 , which means:

From /24 → each /26 block gives 64 IPs

So you get 4 subnets total

But the options must be interpreted carefully!

→ Let's calculate again properly:

/26 = 64 addresses per subnet (2⁶)

Usable hosts per subnet = 64 - 2 = 62

Number of subnets in /24 when divided by /26 = 2^(26 - 24) = 4 subnets

So correct result is:

4 subnets, 62 hosts per subnet → Correct Answer: C

However, Option D says 8 subnets, 30 hosts per subnet , which actually matches a /27 mask , not /26.

Final Correct Answer: C

A /31 subnet in IPv4 provides exactly two IP addresses (e.g., 192.168.1.0/31 → usable: 192.168.1.0 and 192.168.1.1). Traditionally, these would represent a network address and a broadcast address , but RFC 3021 redefines /31 subnets for point-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's ideal for point-to-point links , saving address space.

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