4A0-100 Exam Dumps : Nokia IP Networksand Services Fundamentals

Tier 1 ISPs: Haveglobal reachabilityand exchange traffic via peering. Theydo not payfor transit.

Tier 2 ISPs: Purchasetransit services from Tier 1and provide transit to Tier 3 or other Tier 2 ISPs.

Tier 3 ISPs: Providelast-mileconnectivity to end users and donot provide transit services.

Option A is correct– Tier 1 and Tier 2provide transit services.

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

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

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

Every router constructs acomplete map of the network topology.

Then each router runs theSPF algorithmto compute optimal paths.

Option C is correct– routers know theentire network topology.

Option A isDistance Vector behavior(e.g., RIP).

Option B isnot efficient or accurate for Link-State.

Option D –hop-countis used inDistance Vector(e.g., RIP).