Nokia 4A0-100 Exam Dumps

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 goal of this model. In fact, the encapsulation and interaction between layers can sometimes introduce extra overhead. This overhead is a trade-off accepted to gain the other benefits listed above.

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'

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

The system interface in Nokia SR OS is a loopback-style logical interface that represents the router itself. It is used for:

Router ID assignment (if not manually set)

Source IP for control-plane protocols (OSPF, BGP)

Reachability testing

Important properties:

It is type loopback

It exists by default

If router ID is unset, it uses the system IP address

But the IP address on the system interface does not need to be /32

It can have other prefix lengths, especially in service provider scenarios.

Thus, Option B is FALSE.

Nokia SRA Study Guide -- Chapter: 'System Interface and Loopbacks'

Nokia SR OS Fundamentals Guide -- System IP Configuration Section

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

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

Every router constructs a complete map of the network topology.

Then each router runs the SPF algorithm to compute optimal paths.

Option C is correct -- routers know the entire network topology.

Option A is Distance Vector behavior (e.g., RIP).

Option B is not efficient or accurate for Link-State.

Option D -- hop-count is used in Distance Vector (e.g., RIP).

Nokia SRA Study Guide -- Chapter: ''OSPF and IS-IS Concepts''

RFC 2328 -- OSPF Link-State Overview