How many layers are in OSI reference model?

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OSI reference model: OSI reference model is an ISO standard which defines a networking framework for implementing the protocols in seven layers. These seven layers can be grouped into three categories: o Network layer: Layer 1, Layer 2 and layer 3 are the network layers. o Transport layer: Layer 4 is a transport layer. o Application layer. Layer 5, Layer 6 and Layer 7 are the application layers. There are 7 layers in the OSI reference model. 1. Physical Layer o It is the lowest layer of the OSI reference model. o It is used for the transmission of an unstructured raw bit stream over a physical medium. o Physical layer transmits the data either in the form of electrical/optical or mechanical form. o The physical layer is mainly used for the physical connection between the devices, and such physical connection can be made by using twisted-pair cable, fibre-optic or wireless transmission media. 2. DataLink Layer o It is used for transferring the data from one node to another node. o It receives the data from the network layer and converts the data into data frames and then attach the physical address to these frames which are sent to the physical layer. o It enables the error-free transfer of data from one node to another node. Functions of Data-link layer: o Frame synchronization: Data-link layer converts the data into frames, and it ensures that the destination must recognize the starting and ending of each frame. o Flow control: Data-link layer controls the data flow within the network. o Error control: It detects and corrects the error occurred during the transmission from source to destination. o Addressing: Data-link layer attach the physical address with the data frames so that the individual machines can be easily identified. o Link management: Data-link layer manages the initiation, maintenance and, termination of the link between the source and destination for the effective exchange of data. 3. Network Layer o Network layer converts the logical address into the physical address. o It provides the routing concept means it determines the best route for the packet to travel from source to the destination. Functions of network layer: o Routing: The network layer determines the best route from source to destination. This function is known as routing. o Logical addressing: The network layer defines the addressing scheme to identify each device uniquely. o Packetizing: The network layer receives the data from the upper layer and converts the data into packets. This process is known as packetizing. o Internetworking: The network layer provides the logical connection between the different types of networks for forming a bigger network. o Fragmentation: It is a process of dividing the packets into the fragments. 4. Transport Layer o It delivers the message through the network and provides error checking so that no error occurs during the transfer of data. o It provides two kinds of services: o Connection-oriented transmission: In this transmission, the receiver sends the acknowledgement to the sender after the packet has been received. o Connectionless transmission: In this transmission, the receiver does not send the acknowledgement to the sender. 5. Session Layer o The main responsibility of the session layer is beginning, maintaining and ending the communication between the devices. o Session layer also reports the error coming from the upper layers. o Session layer establishes and maintains the session between the two users. 6. Presentation Layer o The presentation layer is also known as a Translation layer as it translates the data from one format to another format. o At the sender side, this layer translates the data format used by the application layer to the common format and at the receiver side, this layer translates the common format into a format used by the application layer. Functions of presentation layer: o Character code translation o Data conversion o Data compression o Data encryption 7. Application Layer o Application layer enables the user to access the network. o It is the topmost layer of the OSI reference model. o Application layer protocols are file transfer protocol, simple mail transfer protocol, domain name system, etc. o The most widely used application protocol is HTTP(Hypertext transfer protocol ). A user sends the request for the web page using HTTP.

Question:- What is the usage of OSI physical layer?

Answer:- The OSI physical layer is used to convert data bits into electrical signals and vice versa. On this layer, network devices and cable types are considered and setup.

Question:- Explain the functionality of OSI session layer?

Answer:- OSI session layer provides the protocols and means for two devices on the network to communicate with each other by holding a session. This layer is responsible for setting up the session, managing information exchange during the session, and tear-down process upon termination of the session.

Question:- What is the maximum length allowed for a UTP cable?

Answer:- The maximum length of UTP cable is 90 to 100 meters.

Question:- What is RIP?

Answer:- • RIP stands for Routing Information Protocol. It is accessed by the routers to send data from one network to another. • RIP is a dynamic protocol which is used to find the best route from source to the destination over a network by using the hop count algorithm. • Routers use this protocol to exchange the network topology information. • This protocol can be used by small or medium-sized networks.

Question:- What do you understand by TCP/IP?

Answer:- TCP/IP is short for Transmission Control Protocol /Internet protocol. It is a set of protocol layers that is designed for exchanging data on different types of networks.

Question:- What is netstat?

Answer:- The "netstat" is a command line utility program. It gives useful information about the current TCP/IP setting of a connection.

Question:- What do you understand by ping command?

Answer:- The "ping" is a utility program that allows you to check the connectivity between the network devices. You can ping devices using its IP address or name.

Question:- What is Sneakernet?

Answer:- Sneakernet is the earliest form of networking where the data is physically transported using removable media.

Question:- Explain the peer-peer process.

Answer:- The processes on each machine that communicate at a given layer are called peer-peer process.

Question:- What is a congested switch?

Answer:- A switch receives packets faster than the shared link. It can accommodate and stores in its memory, for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped. This state is called a congested state.

Question:- What is multiplexing in networking?

Answer:- In Networking, multiplexing is the set of techniques that is used to allow the simultaneous transmission of multiple signals across a single data link.

Question:- What is RSA Algorithm?

Answer:- RSA is short for Rivest-Shamir-Adleman algorithm. It is mostly used for public key encryption.

Question:- How many layers are in TCP/IP?

Answer:- There are basic 4 layers in TCP/IP: 1. Application Layer 2. Transport Layer 3. Internet Layer 4. Network Layer

Question:- What is the difference between TCP/IP model and the OSI model?

Answer:- • TCP/IP model • Full form of TCP is transmission control protocol. • TCP/IP has 4 layers. • TCP/IP is more reliable than the OSI model. • TCP/IP model uses horizontal approach. • TCP/IP model uses both session and presentation layer in the application layer. • TCP/IP model developed the protocols first and then model. • In Network layer, TCP/IP model supports only connectionless communication. • TCP/IP model is a protocol dependent. • OSI model • Full form of OSI is Open System Interconnection. • OSI has 7 layers. • OSI model is less reliable as compared to the TCP/IP model. • OSI model uses vertical approach. • OSI Reference model uses separate session and presentation layers. • OSI model developed the model first and then protocols. • In the Network layer, the OSI model supports both connection-oriented and connectionless communication. • OSI model is a protocol independent.