Introduction to Data-Link Layer

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Questions and Answers

What is the role of the data-link layer in the TCP/IP protocol suite?

It defines protocols for physical layer communication.

It provides node-to-node communication and services to the network layer. (correct)

It manages the connection between various networks.

It exclusively handles routing decisions for data packets.

How does a data unit travel across the Internet according to the data-link layer?

It utilizes only wireless networks for transmission.

It is processed by the application layer before any travel.

It travels directly from source to destination in one step.

It must pass through many nodes interconnected by links. (correct)

What happens to a datagram at the data-link layer of the sending node?

It is encapsulated into a frame before being sent. (correct)

It is forwarded directly to the final destination.

It is split into multiple packets for easier handling.

It is only decapsulated before transmission.

What must the data-link layer of each intermediate node do when a data packet is transiting?

Both encapsulate and decapsulate the datagram. Signup and view all the answers

Which statement best describes the relationship between the data-link layer and the physical layer?

The data-link layer receives services from the physical layer. Signup and view all the answers

What type of connections characterize communication at the data-link layer?

Node-to-node connections. Signup and view all the answers

What is the primary function of the framing service provided by the data-link layer?

To encapsulate the datagram in a frame before transmission. Signup and view all the answers

What is the primary function of links in the context of the data-link layer?

To physically connect nodes in a network. Signup and view all the answers

Which scenario illustrates the need for flow control in data-link layers?

The producer generates frames at a much faster rate than the consumer can process. Signup and view all the answers

What happens when the buffer at the receiving data-link layer becomes full?

It sends a signal to the sender to slow down or stop transmission. Signup and view all the answers

Why might several standard protocols exist in the data-link layer?

To address diverse types of networks and communication needs. Signup and view all the answers

How is error control typically managed in the data-link layer?

By detecting errors and either correcting or retransmitting frames. Signup and view all the answers

What is the significance of transforming frames into bits at the sending node?

It is necessary for the frame to be transmitted over the electromagnetic signals. Signup and view all the answers

What happens if the destination IP address in a datagram is changed?

The packet never reaches its destination. Signup and view all the answers

What is another term used synonymously with link-layer address?

MAC address Signup and view all the answers

What strategy is NOT typically used for flow control in data-link layers?

Using an unlimited buffer for all incoming frames. Signup and view all the answers

Which of the following is true regarding framing in data-link layers?

Frames may contain both a header and a trailer. Signup and view all the answers

How do link-layer addresses change as a frame moves from one link to another?

They are changed every time the frame transitions between links. Signup and view all the answers

Why is error detection and correction significant in the data-link layer?

It helps ensure the integrity of frames during transmission. Signup and view all the answers

What type of address is used for one-to-one communication?

Unicast address Signup and view all the answers

Which type of address allows for communication to all entities in a link?

Broadcast address Signup and view all the answers

What protocol helps a node obtain the link-layer address associated with an IP address?

Address Resolution Protocol (ARP) Signup and view all the answers

What type of address facilitates one-to-many communication within a local link?

Multicast address Signup and view all the answers

What is the role of the last router in the forwarding path of a datagram?

It knows the IP address of the destination host. Signup and view all the answers

What is typically considered an issue in the network layer or the transport layer instead of the data-link layer?

Congestion control Signup and view all the answers

In a point-to-point link, how is the medium utilized?

It is dedicated to two devices. Signup and view all the answers

Which sublayer of the data-link layer deals specifically with issues related to broadcast links?

Media access control (MAC) Signup and view all the answers

What types of links can data-link layers control?

Both point-to-point and broadcast links Signup and view all the answers

Why can a datagram in the Internet not reach its destination using only IP addresses?

Each datagram may take a different path. Signup and view all the answers

What is a characteristic of a broadcast link?

It allows multiple pairs of devices to communicate simultaneously. Signup and view all the answers

What does the data link control (DLC) sublayer manage?

All issues common to both point-to-point and broadcast links Signup and view all the answers

In the context of frames and link-layer protocols, what is a common outcome of congestion?

Frame loss Signup and view all the answers

What is the primary purpose of the Address Resolution Protocol (ARP)?

To map an IP address to a link-layer address Signup and view all the answers

What occurs when a host sends an ARP request packet?

The query is broadcasted over the link using a broadcast address Signup and view all the answers

Which layer of the network model does the Address Resolution Protocol belong to?

Network layer Signup and view all the answers

When Alice needs to send data to Bob, what information must she already have?

Bob's network-layer (IP) address Signup and view all the answers

What type of address does ARP return when it resolves an IP address?

Link-layer address Signup and view all the answers

Which of the following best describes a node in the context of the Internet?

A device that connects to a network, such as a host or router Signup and view all the answers

What type of addresses does ARP use in its request packet?

Both link-layer and IP addresses of sender, and IP address of receiver Signup and view all the answers

What happens to packets in the Internet as they traverse its architecture?

They travel through a set of nodes and links Signup and view all the answers

Why is it important not to change an end-to-end address from the source to the destination?

It ensures data integrity throughout the transmission. Signup and view all the answers

How many IP addresses and link-layer addresses should a router possess when connected to five links?

Five IP addresses and five link-layer addresses. Signup and view all the answers

In a private small internet configured in a mesh topology, are routers necessary?

No, because all hosts connect directly. Signup and view all the answers

Why may a router be needed in a specific communication scenario?

To enable communication between different network segments. Signup and view all the answers

What type of switching does the current Internet use at the data-link layer?

Packet-switching exclusively. Signup and view all the answers

What happens if system B does not run the ARP program?

System A will fail to deliver packets to system B. Signup and view all the answers

What should system A do before broadcasting an ARP request to map from N2 to L2?

Always check its cache for existing mappings. Signup and view all the answers

What is the difference between a forwarding table and ARP in terms of mapping?

A forwarding table maps IP addresses to link-layer addresses, while ARP maps link-layer addresses to IP addresses. Signup and view all the answers

Study Notes