Computer engineering 👩‍🎓Important educational notes📚

  Solution:- Topology Geometric representation of how the computers are connected to each other is known as topology.  There are five types of topology – Bus, Star, Mesh, Ring and Hybrid . Bus Topology   •  Bus topology is a network setup in which each computer and network device are connected to a single cable or backbone by the help of interface connectors. This central  cable is the backbone of the network and is known as Bus.  •  Every workstation  communicates with the other device through this Bus. A signal from the source is  broadcasted and it travels to all workstations connected to bus cable.  •  Although the  message is broadcasted but only the intended recipient, whose MAC address or IP  address matches, accepts it. If the MAC /IP address of machine doesn’t match with the  intended address, machine discards the signal.  •  A terminator is added at ends of the  central cable, to prevent boun...

Solution:- Different IP address classes in IPv4:- Class A, Class B, Class C, Class D, Class E.  Class A : Class A IP address format is given below: In this, the first bit is ‘0’. The next 7 bits are used indicate network id. Rest of the 3 bytes are used to indicate host id. Thus the First Byte in Class A type of IP address will have a range from 0 to 126. Example : 10.1.2.1 In this, the first byte ‘10’ has first bit 0, and hence it belongs to class A IP address. Class B :  Class B IP address format is given below: In this, the first two bits are ‘1 0’. The next 14 bits are used indicate network id. Rest of the 2 bytes are used to indicate host id.  Thus, the first byte of class B type of IP address has a range from 128 to 191. Example : 187.4.5.1 In this address, the first byte ‘187’ has first two bits as 10. Class C : Class C IP address format is given below: In this, the first three bits are ‘1 1 0’. The next 21 bits are used indicate network id. Rest of the One byt...

  Solution:- OSI model (open system interconnection) model was developed by ISO (international standard organization) Function of OSI model: i. It provides way to understand how internetwork operates.  ii. It gives guideline for creating network standard. OSI model has 7 layers as shown in the figure.  OSI model has following 7 layers as Physical layer, data link layer, Network layer, Transport layer, session layer, presentation layer, application layer.  1. Physical layer: 1. It co-ordinates the functions required to transmit bit stream over physical medium. 2. It deals with mechanical and electrical specifications of interface and transmission medium. Functions of physical layer are: Physical characteristics of interfaces and media.  Representation of bits: Data rate (transmission rate).  Synchronization of bits.  Line configuration: Point to point or multipoint configuration should be used.  2. Data link layer: 1. It is responsible for transmit...

Solution:-   TCP/IP Reference Model: TCP/IP means transmission control protocol and internet protocol.  Protocols are set of rules which govern every possible communication over the internet.  These protocols describe the movement of data between the host computers or internet. These offer simple naming and addressing schemes.  It is robust to failures and flexible to diverse networks. Most widely used protocol for interconnecting computers and it is the protocol of the internet.  Description of different TCP/IP layers   Layer 1: Host-to-network Layer   1. Protocol is used to connect the host, so that the packets can be sent over it.  2. Varies host to host and network to network.  Layer 2: Internet layer  1. Selection of a packet switching network which is based on a connectionless internetwork layer is called internet layer.  2. It the layer which holds the whole architecture together.  3. It allows the host to insert th...

  Solution:- 1. A gateway is a node (router) in a computer network, a key stopping point for data on its way to or from other networks.  2. Gateway is protocol converter.  3. Gateway enables communication between different network architecture and environments.  4. It works at all layers of OSI model.  Operations of Gateway: 1. Gateway connects two systems that do not use the same protocol, data format, language and architecture.  2. Convert commonly used protocols (e.g. TCP/IP) to a specialized protocol (for example, an SNA: System Network Architecture).  3. Convert message formats from one format to another. It translates different addressing schemes  4. Using gateways, we are able to communicate and send data back and forth. The Internet wouldn't be any use to us without gateways (as well as a lot of otherhardware and software). 5. A gateway is a node (router) in a computer network, a key stopping point for data on its way to or from other netw...

  Solution:- Diagram:- Explanation:- 1. Client server Architecture consists of Client computers or nodes, which are connected to centralized server.  2. The servers stores all the network's shared files and applications programs, such as word processor documents, compilers, database applications, spreadsheets, and the network operating system. 3. Client will send request to access information from the server based on the request server will send the required information to the client. Advantages of Client Server Network: 1. It has the centralized control. i.e. centralized user accounts, security, and access to simplify network administration. 2. It does not slow down with heavy use. 3. The size of the network can be expanded to any size. 4. Proper Management in which all files are stored at the same place. In this way, management of files becomes easy. Also it becomes easier to find files. 5. As all the data is stored on server it’s easy to make a back-up of it. 6. Reduce...

  Solution :- Diagram :- Explanation:  1. File Transfer Protocol (FTP) is the standard mechanism provided by TCP/IP for copying a file from one host to another. Figure shows the basic model of FTP. 2. The client has three components: user interface, client control process, and the client data transfer process. The server has two components: the server control process and the server data transfer process.  3. The control connection is made between the control processes. The data connection is made between the data transfer processes.  4. The control connection remains connected during the entire interactive FTP session.  5. The data connection is opened and then closed for each file transferred. It opens each time commands that involve transferring files are used, and it closes when the file is transferred. In other words, when a user starts an FTP session, the control connection opens. While the control connection is open, the data connection can be opened and c...

  Solution :-  1. A domain namespace is a name service provided by the Internet for Transmission Control Protocol networks/Internet Protocol (TCP/IP).  2. DNS is broken up into domains, a logical organization of computers that exist in a larger network. 3. The DNS database hierarchical naming scheme is called a domain name space.  4. Each node in the hierarchy represents a partition of the DNS database.  5. The nodes are known as domains, and each of them must have a name as the DNS database is indexed by name. When you add domains to the hierarchy, the name of the parent domain is appended to the domain, which becomes a child domain or subdomain. 6. The hierarchical structure of the domain name space consists of a root domain, top-level domains, second level domains, subdomains, and host names. The Root Domain is at the top of the hierarchy and is represented by a period (.). Top-Level Domains are two or three-character name codes, representing organisation t...

  Solution :- Segmentation: 1. Segmentation is the term used to describe the process of dividing streams of data into smaller chunks.  2. Segmentation usually occurs fairly early in the communication process and it is almost always software that performs the segmentation process.  3. The segmentation process is performed prior to transfer of data across a network or before storage on a peripheral device.  4. Segmentation is necessary because today's communication systems use what is called packetized communication. 5. A message is divided into segments; each segment contains sequence number, which enables this layer in reassembling the message. Reassembly:  1. Reassembly is the reverse of segmentation. Protocol Data Units are put back together in the correct order to reassemble a stream of data in its original form. 2. Message is reassembled correctly by arranging them sequence number wise; upon arrival at the destination and replaces packets which were lost in ...

Solution :- SLIP 1. Serial Line Protocol is an encapsulation of the Internet Protocol designed to work over serial ports and modem connections. 2. This packet-framing protocol and defines a sequence of bytes that frame IP packets on a serial line. 3. SLIP is commonly used for point-to-point serial connections running TCP/IP 4. It is designed to transmit signals over a serial connection and has very low overhead. 5. SLIP is serial line internet protocol 6. SLIP does not perform error detection and correction. 7. SLIP does not provide any authentication. 8. SLIP is not approved internet standard. 9. SLIP supports static IP address assignment PPP   1. PPP is point to point protocol. 2. It is a much more developed protocol than SLIP(which is why it is replacing it). 3. It transfers additional data, better suited to data transmission over the Internet(the addition of data in a frame is mainly due to the increase in bandwidth). 4. PPP perform error detection  5. PPP provides authent...

  Solution:-  Bluetooth is short range wireless technology.  Range of Bluetooth is 10 meters.  Bluetooth Architecture defines 2 types of networks.  1)Piconet  2)Scatternet  Piconet   1. It consists of 1 master node and 7 slave nodes.  2. Piconet have 8 active nodes (7+1) in the range of 10 meters.  3. There can be only 1 master station in each piconet. 4. Communication is between master and slave  5. Slave-slave communication is not possible.  6. Piconet can have 255 parked nodes, that cannot take part in communication  7. There will be 7 slaves in active state and 255 nodes in parked state.  Scatternet   1. It is formed by combining various piconets.  2. Slave in one piconet can act as master in other piconet.  3. Such a node can receive message from the master in the first piconet and  deliver the message in second piconet.  4. Station can be member of two piconets.  5. Station cannot b...

  Solution :-   Tree Topology: 1. A tree topology is cascading of star. 2. As in a star, nodes in a tree are linked to a central hub head end that controls the traffic to a network. However, not every computer plugs into the central hub, majority of them are connected to a secondary hub which in turn is connected to the central hub as shown in fig. 3. The central hub head is either a switch or a router. 4. The central hub contains a repeater, which looks at the incoming bits and 99 regenerates them afresh as full blown signals for 0 or 1 as per case.  5. This allows the digital signals to traverse over longer distances.  6. Therefore, the central hub is also called active hub.  7. The tree topology also contains many secondary hubs, which may be active hubs or passive hubs.

  Solution :- In computer networking, the term encapsulation is used to refer to the process of each layer at the sending computer adding its own header information, in the form of meta-data to the actual payload (data)  To satisfy all the requirements, the protocols operating at the various layers work together to supply a unified quality of service. In a typical transaction, an application layer protocol (which includes presentation and session layer functions) generates a message that is passed down to a transport layer protocol. The protocol at the transport layer has its own packet structure, which is known as a protocol data unit (PDU). PDU includes specialized header field and a data field that carries the payload. The payload is the data received from the application layer protocol. The transport layer encapsulates the application layer data and then passes it down to the next layer. The network layer protocol then receives the PDU from the transport layer and encapsul...

  Solution :-   Network layer: The network layer in a network model is responsible for the source-to-destination delivery of a packet, possibly across multiple network models (links).  The network layer in a network model ensures that each packet gets from its point of origin to its final destination. If two systems are connected to the same link, there is usually no need for a network layer in a network model.  However, if the two systems are attached to different network models (links) with connecting devices between the network models (links), there is often a need for the network layer in network model to accomplish source-to-destination delivery.  Following Figure shows the relationship of the network layer to the data link and transport layers in a network model.         Figure: Network layer in a network model The network layer in a network model is responsible for the delivery of individual packets from the source host to the destinat...

  Solution :- Ans Data link layer: Data link layer is the second layer of the OSI model. It accepts the data from the Network layer, attaches header & trailer and send it to the physical layer. At receives side it accepts the data from the physical layer snip of header & footer & gives back to network layer the way it has taken.  Working: It is responsible for transmitting group of bits between the adjacent nodes.  The group of bits is called as frame.  The data link in a network model layer transforms the physical layer, a raw transmission facility, to a reliable link.  It makes the physical layer appear error-free to the upper layer (network layer).  Figure shows the relationship of the data link layer to the network and physical layers of network model. The data link layer in a network model is responsible for moving frames from one node to the next. Other responsibilities of the data link layer in a network model include the following: 1. Fr...

  Solution :- Cellular telephony uses Analog transmission. Frequency modulation is used for communication between the mobile phone and the cell office. Two frequency bands are allocated for this purpose: i. Communication that is initiated by the mobile phone. ii. Communication that is initiated by landline phone. Full duplex operation is possible by separating transmit and receive signals into separate frequency bands. Cellular phone units transmit in the lower band of frequencies, 825 to 845 MHz, and receive in the higher band, 870 to 890 MHz Within these two bands, 666 separate channels (333 channels per band) have been assigned for voice and control.  Each channel requires a full-duplex dialog. For preventing interference, adjacent channels are rarely allocated. Some channels are also required for control purpose. This reduces the number of channels available for the cell. Each channel occupies a bandwidth of 30 kHz.

Solution :-  Unshielded twisted pair is the most common kind of copper telephone wiring.  Twisted pair is the ordinary copper wire that connects home and many business computers to the telephone company.  To reduce crosstalk or electromagnetic induction between pairs of wires, two insulated copper wires are twisted around each other. Each signal on twisted pair requires both wires. Connectors: i. The most common UTP connector is RJ45 (RJ stands for Registered Jack). ii. The RJ45 is a keyed connector (the connector can be inserted in only one way). Application: 1. Local Area Networks, such as 10Base-T and 100Base-T, use twisted pair cable. 2. The most common application of the twisted pair is also the telephone system.Labelled 

Solution :-   Ring topology: In a ring topology, each computer or node is connected to the next node and the last computer is connected to the first computer as shown in the diagram below.  Diagram of Ring topology Thus, each computer has a dedicated point to point connection with only the two computers on either side of it.  A signal is passed along the ring in one direction, from computer to computer, until it reaches its destination.  In ring topology, each computer on the ring receives the data unit from the previous computer, regenerates it, and forwards it to the next computer.  Working: Every computer on the ring is responsible for passing the token or creating a new one. When a computer has information to send, it creates the token and passes it on. Once the token reaches its final destination, it lets the sender know it arrived safely; the sender then makes a new token and the process starts over. Most ring networks use fiber or twisted pair cable for t...

 NIC (Network interface card / network adapter):  It physically makes the connection, works as interface between computer and network cable.  Functions of NIC:  1. Establishes and manages the computer’s network connection. 2. Translates digital computer data into signals (appropriate for the networking medium)  for outgoing messages, and translates signals into digital computer data for incoming messages 3. Provide physical link or connectivity between computer and the network physical medium. 4. Creates, sends, and receives frames – Frame: fundamental unit of data for network transmission and reception. 5. Manages access to medium. 6. Control flow of data between computer and physical medium. 7. Acts as gatekeeper (permits inbound communications aimed only at its computer (or broadcast) to pass through NIC and on to CPU) – Each card has a unique MAC address in ROM  – Promiscuous mode disables gatekeeper functions

  Characteristics of satellite microwave transmission: In satellite communication, signal transferring between the sender and receiver is done with the help of satellite.  In this communication, electromagnetic waves are used as carrier signals. These signals carry the information such as voice, audio, video or any other data between ground and space and vice-versa. The transmission of signal from first earth station to satellite through a channel is called as uplink. The frequency with which, the signal is sent into the space is called as Uplink frequency (6Hz).  The satellite transponder converts this signal into another frequency and sends it down to the second earth station. A transponder is used to increase the strength of the received signal and change the frequency band of the transmitted signal from the received one.  The transmission of signal from satellite to second earth station through a channel is called as downlink. The frequency with which, the signal...

  Classification of computer networks based on geography: LAN - Local Area Network MAN - Metropolitan Area Network WAN - Wide Area Network CAN - Campus Area Network PAN - Personal Area Network PAN: 1. A PAN is personal area network is used for communication among computer devices close to one’s person. 2. Wireless networking or Bluetooth technologies are the some examples of PAN. The communication network established for the purpose of connecting computer devices of personal use is known as the PAN. CAN: 1. CAN is a Campus Area Network is used to connect buildings across campuses of colleges or Universities. 2. A CAN is actually a type of LAN. 3. It is larger than a LAN but smaller than MAN. CAN is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex or military base. LAN: 1. LAN is local area network. LAN is privately-owned networks covering a small geographic area(less than 1 km), ...

  1)Hub : Hub connects all nodes in star topology. Hub is broadcasting device. It sends packets to all nodes in the network. It works at Physical Layer of OSI model. 2) Repeater : Repeaters are used to take the distorted, weak and corrupt input signal and regenerate this signal at its output. It ensures that the signals are not distorted or weak before it reaches the destination. It increases the signal strength. 3)Bridge : A bridge device filters data traffic at a network boundary. Bridges reduces the amount of traffic on a LAN by dividing it into two segments. It inspects incoming traffic and decides whether to forward or discard it. It sends packets between two networks of same type. 4)Router : Router chooses the best path for packet forwarding. Router read complex network address in packet. It works at Network Layer of OSI model Efficiently direct packets from one network to another, reducing excessive traffic. Join neighbouring or distant network Connect dissimilar networks. P...

Optical fibre advantages: Higher bandwidth : Fiber-optic cable can support dramatically higher bandwidths (and hence data rates) than either twisted-pair or coaxial cable  Less signal attenuation: Fiber-optic transmission distance is significantly greater than that of other guided media. A signal can run for 50 km without requiring regeneration.  Immunity to electromagnetic interference: Electromagnetic noise cannot affect fiber-optic cables. Resistance to corrosive materials: Glass is more resistant to corrosive materials than copper. Light weight: Fiber-optic cables are much lighter than copper cables. Greater immunity to tapping: Fiber-optic cables are more immune to tapping than copper cables. Copper cables create antenna effects that can easily be tapped. Lesser number of repeater:- Electrical isolation: - Optical fibres are fabricated from glass or plastic polymers which are electrical insulators. Hence they do not exhibit earth loop.  Signal security: - The lig...

  Types of hubs:  1) Passive 2) Active 3) Intelligent  Passive Hubs: A passive hubs simply combines the signals of a network segments. There is no signal processing or regeneration.  A passive hub reduces the cabling distance by half because it does not boost the signals and in fact absorbs some of the signal.  With the passive hub each computer receives the signal sent from all the other computers connected to the hub. Active hubs: They are like passive hubs but have electronic components for regeneration and amplification of signals.  by using active hubs the distance between devices can be increased.  The main drawback of active hubs is that the amplify noise along with the signals. They are also much expensive than passive hubs.  Intelligent hubs: in addition to signal regeneration, intelligent hubs perform some network management and intelligent path selection.  One advantage to this is that all transmission media segment can be conne...

 1. Install the printer drivers: In order to share a printer, it must be installed on the computer it is connected to. Most modern printers connect via USB and will install automatically when they are connected. 2. Open the Control Panel: You can access the Control Panel in Windows 7 by clicking the Start menu and selecting Control Panel. In Windows, press ⊞Win+X and select Control Panel from the menu. 3. Open the Network and Sharing Center: If your Control Panel is in Category view, click "Network and Internet", and then select "Network and Sharing Center". Click on "Network and Internet". If your Control Panel is in Icon view, click the "Network and Sharing Center" icon. 4. Click the "Change advanced sharing settings" link. This is located in the left navigation pane of the Network and Sharing Center. 5. Expand the profile you need to change. You will see three different options when you open the "Advanced share settings": P...

Working of TCP/IP Model : TCP/IP uses the client/server model of communication in which a user or machine (a client) is provided a service (like sending a web page) by another computer (a server) in the network.Collectively, the TCP/IP suite of protocols is classified as stateless, which means each client request is considered new because it is unrelated to previous requests. Being stateless frees up network paths so they can be used continuously. The transport layer itself, however, is stateful. It transmits a single message, and its connection remains in place until all the packets in a message have been received and reassembled at the destination. TCP/IP model layers TCP/IP functionality is divided into four layers, each of which include specific protocols. The application layer provides applications with standardized data exchange. Its protocols include the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol 3 (POP3), Simple Mail Transfer Protoco...

There are two types of Computer networks in this category: 1. Broadcast Networks:   In broadcast networks, a single communication channel is shared among all the computers of the network. This means, all the data transportation occurs through this shared channel. The data is transmitted in the form of packets. The packets transmitted by one computer are received by all others in the network. The destination of packet is specified by coding the address of destination computer in the address field of packet header. On receiving a packet, every computer checks whether it is intended for it or not. If the packet is intended for it, it is processed otherwise, it is discarded. There is another form of broadcast networks in which the packets transmitted by a computer are received by a particular group of computers. This is called as "Multicasting". 2. Point to Point or Store and Forward Networks:   The store and forward networks consist of several interconnected computers and networ...

network operating systems salient features are:   Basic support for operating systems like protocol and processor support, hardware detection and multiprocessing. Printer and application sharing. Common file system and database sharing. Network security capabilities such as user authentication and access control. Directory Services Backup and web services. Internetworking of various resources connected in the network Providing access to remote printers, managing which users are using which printers when, managing how print jobs are queued, and recognizing when devices aren't available to the network. Enabling and managing access to files on remote systems, and determining who can access what—and who can't. Granting access to remote applications and resources, such as the Internet, and making those resources seem like local resources to the user (the network is ideally transparent to the user). Providing routing services, including support for major networking protocols, so that...

              OSI                    TCP/IP 1. OSI is a generic, protocol independent standard, acting as a communication gateway between the network and end User. 1. TCP/IP model is based on standard Protocol around which the Internet has developed. It is a communication protocol, which allows connections of hosts over a network. 2. In OSI model the transport layer Guarantees the delivery of packets. 2. In TCP/IP model the transport layer does not guarantee delivery of packets. Still the TCP/IP model is more reliable. 3. Follows vertical approach. 3. Follows horizontal approach. 4. OSI is a reference model around which the networks are built.   Generally, it is used as a guidance tool. 4. TCP/IP model is, in a way implementation of the OSI model. 5. Network layer of OSI...

                               IPv4                                   IPv6 1. Source and Destination addresses are 32 bits in length. 1. Source and Destination addresses are 128 bits in length. 2. IPv4 addresses are binary numbers represented in decimals. 2. IPv6 addresses are binary numbers represented in hexadecimals. 3. IPsec supports in optional. 3. IPsec is inbuilt. 4. Security is dependent on application. 4. IPsec is inbuilt in IPv6 protocol. 5. No packet flow identification. 5. Packet flow identification is available within the IPv6 header using flow label field. 6. Header includes a checksum. 6. Header does not include a checksum. 7. Encryption and Aut...

    Peer to Peer Network    Client Server Network 1. It is much like company uses decentralized management. 1. It is much like company uses centralized management. 2. In this each machine has same power. 2. In this server has more power and client has less power. 3. Uses less expensive computer hardware. 3. It is hardware intensive. 4. Easy to setup and administrator. 4. Complex to setup and require professional administrator. 5. less secure. 5. Very secure 6. Network O.S not required. 6. Network O.S required. 7. It support small Network. 7. It support large Network. 8. Might hurt user’s performance. 8. Better performance.

Benefits of computer network:  File sharing: Computer networks allow file sharing and remote file access. A person sitting at one workstation connected to a network can easily see files present on another workstation, provided he/she is authorized to do so.  Resource Sharing: A computer network provides a cheaper alternative by the provision of resource sharing. All the computers can be interconnected using a network and just one modem & printer can efficiently provide the services to all users. Inexpensive set-up: Shared resources means reduction in hardware costs. Shared files means reduction in memory requirement, which indirectly means reduction in file storage expenses.  Flexible Handling: A user can log on to a computer anywhere on the network and access his/her files. This offers flexibility to the user as to where he/she should be during the course of his/her routine. Centralized Management- Networking allows the management of various resources in the organ...

                                         Hub                                      Switch 1. It users broadcast technology. 1. It uses point to point technology. 2. It send the received packet to all ports. 2. It only send packet to only destination port. 3. Hub is less intelligent device. 3. Switch is more intelligent device. 4. Hub is passive device(without software). 4. Switch is active device(with software). 5. Hub is less expensive. 5. Switch is Expensive. 6. 4/12 port. 6. 24/48 po...