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

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.​

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

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

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

Option Brefers to best path selection (not summarization).

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

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

AP router (Provider router)is locatedin the core of the service provider’s network. Its functions include:

ForwardingMPLS-labeled packetsbetweenPE routers.

Not interacting directly with customer routes or routing instances.

Having no knowledge ofVPN routing or customer-specific services.

Option C is correct– P routers sit in theMPLS core, isolated from customer edge.