Computer Networking Concepts

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Questions and Answers

What is the primary difference between connection-oriented and connectionless services?

Connection-oriented requires a session to be established before communication. (correct)

Connection-oriented services are always more reliable than connectionless ones.

Connectionless services use a common channel for all messages.

Connectionless services require the sender to wait for an acknowledgment.

Which of the following correctly defines a service primitive?

A rule that governs how messages are formatted between layers.

An operation provided by the layer below used for messaging.

A practice of organizing data into packets for transmission.

A system call made to send packets that privileges control to the operating system. (correct)

What is the role of a protocol in networking?

To provide high reliability in all messaging environments.

To outline the format and meaning of messages exchanged within the same layer. (correct)

To connect different layers of the network architecture.

To define the specific operations executed by service primitives.

Which of the following is true about TCP and UDP?

TCP is generally slower than UDP due to its reliability features. Signup and view all the answers

In the context of networking layers, what defines the relationship between services and protocols?

Services are the operations a layer provides to the layer above it. Signup and view all the answers

What is true about the reliability of network services?

Reliability refers to whether messages require acknowledgment. Signup and view all the answers

What does the term 'kernel mode' refer to in networking?

A protected state that allows only the operating system access to hardware resources. Signup and view all the answers

When organizing networking functions, which device link is considered for connectionless communication?

Packet switching technology. Signup and view all the answers

What is the primary role of the Physical Layer in the OSI Reference Model?

Transmission of bits as signals over the channel Signup and view all the answers

Which of the following is NOT a type of cabling used in the Physical Layer?

Circuit Board Signup and view all the answers

What is the primary function of the Network Layer in the OSI Reference Model?

Controls the operation of the subnet and routes packets. Signup and view all the answers

Which of the following protocols is associated with the Transport Layer?

TCP Signup and view all the answers

In the OSI Reference Model, which layer is primarily concerned with the specifications for physical components?

Physical Layer Signup and view all the answers

Which protocol is associated with the Physical Layer for wired communication?

Ethernet (IEEE 802.3) Signup and view all the answers

What mechanism does the Transport Layer provide in terms of data delivery?

End-to-end error control and flow control. Signup and view all the answers

How does the Data-Link Layer differ from the Transport Layer?

Data-Link Layer is concerned with node-to-node communication; Transport Layer is focused on end-to-end delivery. Signup and view all the answers

Which function is NOT provided by the OSI Reference Model?

Manages application user interfaces Signup and view all the answers

What is the primary function of the Session Layer in the OSI Reference Model?

Maintain an ongoing session and manage synchronization Signup and view all the answers

What is a key responsibility of the Network Layer regarding congestion management?

To facilitate congestion control alongside higher layers. Signup and view all the answers

Which of the following is a potential communication method specified by the Physical Layer?

Token Ring (IEEE 802.5) Signup and view all the answers

What type of data transfer does the Transport Layer facilitate?

Process-to-process data transfer. Signup and view all the answers

What is one role of routing protocols within the Network Layer?

To determine the best path for packet delivery across networks. Signup and view all the answers

Which aspect does the Physical Layer NOT manage?

Logical addressing of data Signup and view all the answers

Which of the following accurately describes a service provided by the Transport Layer?

Segmentation of data into packets for better error control. Signup and view all the answers

What does the Physical Layer determine concerning data encoding?

Converting bits to signals Signup and view all the answers

In the context of the OSI Reference Model, which layer deals with data representation and encoding?

Presentation Layer Signup and view all the answers

Which of the following is NOT an example of a functionality provided by the Session Layer?

Encryption and decryption of data Signup and view all the answers

What might the value of the binary number 10010001 represent depending on the interpretation method used?

All of the above Signup and view all the answers

Which system call is used to receive data in socket programming?

read Signup and view all the answers

Which option describes a primary role of the Transport Layer in the OSI model?

Ensure reliable data transfer from end-to-end Signup and view all the answers

Which of the following examples represents the Presentation Layer's responsibilities?

JPEG and MP3 data representation Signup and view all the answers

What aspect of data does the Session Layer primarily focus on?

Synchronization and recovery from failures Signup and view all the answers

Which system call is used to send data in socket programming?

write Signup and view all the answers

What occurs when the server calls 'accept' in socket programming?

It initiates a TCP connection with the client. Signup and view all the answers

In the echo server code, what does the variable 'new_sd' represent?

An identifier for the communicating client. Signup and view all the answers

Which layer of the OSI model is responsible for error control over a physical link?

Data-Link Layer Signup and view all the answers

What is a primary responsibility of the 'fork' function in the echo server?

To handle multiple client connections. Signup and view all the answers

What does the 'close(sd)' function call accomplish in the echo server child process?

It closes the connection with the client. Signup and view all the answers

What is the purpose of the 'write' system call in the echo server?

To send the user's input to the socket. Signup and view all the answers

How is the data read from the socket in the echo server's main loop?

Using a while loop until all data is received. Signup and view all the answers

Which term describes the sequence of actions taken during the echo service between user, client, and server?

Protocol-Service Time diagram. Signup and view all the answers

What happens if the 'fork' function returns -1 in the context of the echo server?

An error occurs, and the program terminates. Signup and view all the answers

Study Notes

Family Tree

Sam and Sally are siblings.
Sam and Sally share the same mother and father.

Network Layers

Network functions in a computing device are organized into layers.
The OSI Model is a 7-layer model.
The TCP/IP Model is a 4-layer model.

Connection-Oriented vs Connectionless

Connection-oriented services require a connection to be established before data transmission and torn down afterward.
Connectionless services allow messages to be transmitted independently, each carrying full destination address information.
Reliability is a characteristic of service, ensuring acknowledgment of messages.

Services and Protocols

Services are collections of operations (primitives) provided by a layer to the one above it.
Protocols define rules for message format and meaning governing communication between peer entities within a layer.

OSI Reference Model

Presents a structured way to connect different systems.
Defines functions at each layer for communication.

Physical Layer

Concerns bits on the wire.
Defines physical components, specifications, and communication methods.
Examples: Ethernet, Token Ring, Wireless (IEEE 802.11n, ac)

Network Layer

Controls subnet operations, focusing on network-wide addressing and routing.
Enables datagram routing from source to destination.
Handles congestion in conjunction with higher layers.
Examples: IP, routing protocols

Transport Layer

Responsible for process-to-process data transfer.
Provides reliable data delivery, segmentation, and end-to-end error and flow control.
Examples: TCP, UDP

Transport Layer vs Data-Link Layer Error Control:

Data-link layer provides error control over a physical link.
Transport layer provides error control over an end-to-end network connection.

Session Layer

Enables ongoing application sessions.
Handles synchronization and checkpointing for recovery in case of crashes.
Examples: Operating systems, Scheduling, Remote Procedure Call (RPC)

Presentation Layer

Focuses on data representation and interpretation.
Handles encryption, decompression, and machine-specific conventions.
Examples: ASCII/EBCDIC, JPEG, MP3

Socket Programming: TCP

The accept() function is used to handle incoming connections from clients on a server.
The fork() system call creates a new process for each client connection, improving server concurrency.

Socket Programming: Echo Server

The read() function is used to receive data from a client.
The write() function is used to send data to a client.
The close() function is used to close a socket connection.

Socket Programming: TCP Protocol-Service Time Diagram

The diagram demonstrates the sequence of events involved in a TCP echo service.
Key steps involve establishing connections, sending and receiving data, and closing sockets.

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Description

Explore key concepts in computer networking including the OSI model, TCP/IP layers, and the differences between connection-oriented and connectionless services. Understand the roles of services and protocols in facilitating communication between devices.