BO2

 Network Devices

1) Repeater

A repeater operates at the physical layer and regenerates signals to prevent them from becoming weak. It does not amplify the signal.

Hub

A hub is essentially a multiport repeater that connects multiple wires. However, it cannot filter data, so data packets are sent to all connected devices.

Types of Hub

- Active Hub: These hubs have their own power supply and can clean, boost, and relay signals along with the network.

- Passive Hub: These hubs collect wiring from nodes and receive power supply from active hubs.

- Intelligent Hub: Similar to active hubs, intelligent hubs also have remote management capabilities. They allow administrators to monitor traffic passing through the hub and configure settings.

Switches

Switches are multiport bridges with buffers. They can perform error checking before forwarding data.

Router

A router is a device similar to a switch that routes data packets based on their IP addresses. It primarily operates at the Network Layer.

Hubs and Network Bandwidth

Network bandwidth refers to the amount of data that can be transferred within a given interval. When all computers are connected to a hub, they must share the available bandwidth provided by the hub.

Wireless Access Points (WAP)

The heart of a wireless network is the wireless access point (WAP).

Network Interface Card (NIC)

Most NICs are built into a computer's motherboard. When a frame arrives at a NIC, it checks the frame's destination MAC address to see if it matches its built-in MAC address.

NIC Driver

Most operating systems come with drivers for a wide range of NICs.

Wireless NICs

Wireless NICs must be chosen based on the type of wireless access point (AP) being used. They connect to the network using a service set identifier (SSID).

Router

Routers are devices that enable multiple LANs to communicate with each other.

Router Work with IP Address and Routing Table

A router uses IP addresses and a routing table to determine where to send packets. If the router doesn't have an entry for a specific destination, it uses a default route. If the network cannot be found and there is no default route, a "network unreachable" message is sent.

Default Gateway

The default gateway is a configuration in a computer's IP address settings.

BO1

 Computer Network & Hardware Essentials

Let's start with the components of a network. Hardware components are essential for network communication. One important component is the Network Interface Card (NIC), which is a circuit board or chip installed on a computer. The NIC allows the computer to connect to the network. Another component is the network medium, which can be a cable that plugs into the NIC or even airwaves for wireless networks. Additionally, interconnecting devices enable communication between two or more computers without a direct connection.

Now, let's talk about the software components of a network. Network client and server software play crucial roles in network communication. The client software, such as the Chrome web browser, requests information stored on network computers. On the other hand, server software, like the Apache web server, allows a computer to share its resources with other computers on the network. Protocols are also important in network communication, as they define the rules and format that computers must use when sending information. An example of a protocol is the TCP/IP protocol stack. Lastly, the NIC driver receives data from protocols and forwards it to the physical NIC.

To understand the network communication process, it's helpful to know the layers involved. The process starts with a user application trying to access a network resource. The client software detects the request and passes the message to the network software. The network protocols then package the message in a suitable format and send it to the NIC driver. Finally, the NIC driver sends the data to the NIC card.

Now, let's delve into how two computers communicate on a LAN (Local Area Network). The most common protocol used on networks is TCP/IP. It consists of a logical address, known as the IP address, and a physical address, called the MAC address. Broadcast IP addressing is designed to facilitate message delivery.

Understanding network terminology is crucial for anyone managing a server. It guides operating system agnostic and helps navigate the profession's own language and acronyms. Additionally, internetworks are collections of LANs tied together, while Personal Area Networks (PANs) are groups of network devices that communicate with various connected devices under private ownership. LANs, on the other hand, are private networks where network devices communicate with each other. Wireless LANs are computer networks that are wireless and link two or more devices in a limited area. Metropolitan Area Networks (MANs) cover larger areas than LANs but can be expensive. Wide Area Networks (WANs) cover even larger areas and may not be owned by a single organization.

Let's also clarify the terminology related to the internet, intranet, and extranet. The internet refers to the worldwide public internetwork, while an intranet is a private internetwork where devices and servers are only available to connected users. An extranet allows limited and controlled access to internal resources by outside users.

Private IP addresses are reserved for private networks. Organizations that distribute IP addresses reserve a range of addresses for private networks. On the other hand, public IP addresses identify us to the wider internet, allowing information to find us. Private IP addresses are used within a private network to securely connect to other devices within the same network.

Lastly, let's discuss packets and frames. A packet is a chunk of data with source and destination IP addresses added to it. A frame, on the other hand, is a packet with source and destination MAC addresses added to it.

In terms of client and server roles, a client can be a workstation running a client operating system or network software on a computer that requests network resources from a server. The client operating system is the OS installed on the computer, while the client computer's primary role is to run user applications and access network resources. Client software is responsible for requesting network resources from a server on another computer. On the other hand, a server is a computer with software installed that provides network services to client computers. The server operating system is designed to share network resources and provide other network services, while the server computer's primary role is to give client computers access to the network server. Server software responds to requests for resources from client software.

We hope this guide has provided you with a better understanding of computer network and hardware essentials. If you have any further questions, feel free to reach out to us.

A03

 Digital Representation

ASCII, which stands for American Standard Code for Information Interchange, is a 7-bit character code with values ranging from 0 to 127. It is a subset of the UTF-8 code and includes control characters and printable characters such as digits, uppercase letters, and lowercase letters. Unicode characters code is a superset of ASCII and contains values from 0 to 10FFFF16.

Representing Sound

In order for the computer to process sounds, they need to be converted to binary. Sound is captured by the microphone and then converted into a digital signal.

Representing Images

Images are broken up into individual pixels for digital representation.

Representing Numbers

Numbers in a computer system are represented by a string of bits called binary numbers. Computers use the binary base 2 number system. Binary digital components, known as transistors, operate in two states - on and off. Hexadecimal (base 16) and octal (base 8) are also used as compact forms for representing binary numbers.

Number System

The decimal (base 10) number system uses 10 symbols (0-9) called digits and utilizes positional notation. The binary (base 2) number system uses two symbols (0 and 1). A binary digit is called a bit, and eight bits make up a byte. The hexadecimal (base 16) number system uses symbols 0-9 and A-F. Hexadecimal numbers are denoted with a suffix "H".

Conversion

Binary to Decimal: Convert binary numbers to decimal using the weighted sum method.

Decimal to Binary: Divide the decimal number by 2 to find the binary number.

Binary to Hexadecimal: Divide the binary number into groups of 4 bits and convert each group to its hexadecimal equivalent.

Hexadecimal to Binary: Convert each hexadecimal digit to its binary equivalent.

Binary to Octal: Divide the binary number into groups of 3 bits and convert each group to its octal equivalent.

Octal to Binary: Convert each octal digit to its binary equivalent.

Number Representation - Signed

Positive numbers remain the same, while negative numbers are represented by complementing the number. There are three ways to represent signed integers: sign and magnitude, 1's complement, and 2's complement.

Addition and Subtraction

In addition, simply add the two numbers. For subtraction, convert the second value by adding 1 to it and then add the converted second value to the first value. Borrowing may be required for subtraction.

Overflow

Overflow occurs when the carried in and carried out bits are not equal. The range for overflow is between +7 and -8. Increasing the width of the range can help control overflow.

A02

 Fetch, Execution, and Input/Output

The central processing unit (CPU) is the heart of the computer.

Data is stored in bits.

- One byte is equal to eight bits.

- A bit is the smallest unit of data measurement.

- It can be either 0 or 1.

- Computers interpret our intentions and process information by converting data into binary forms.

Functional Units

Primary Memory:

- Also known as the main memory.

- Organized into words of typically 32 bits.

- 32 bits contain four 8-bit bytes.

- Programs and their data must be stored in this memory to be executed.

Cache Memory:

- An adjunct to the main memory, fabricated on the processor chip.

- It is smaller and faster memory.

Processor:

- Consists of logic circuits, timing and control circuits, and registers.

Arithmetic and Logic Unit (ALU):

- Most computer operations are executed in the ALU of the processor.

- It performs arithmetic or logic operations.

Control Unit:

- Coordinates the operations of the memory, ALU, and I/O to store and process information.

Computer:

- Accepts information in the form of programs and data through an input unit and stores it in memory.

- The information is fetched under program control into an ALU where it is processed.

- The processed information leaves the computer through an output unit.

- All these operations are directed by the control unit.

Instruction Cycle:

- The computer system can run very complex programs, but its basic operation is simple.

- It repeats basic operations billions of times per second.

- A single cycle of operation is called the instruction cycle.

Instructions and Programs:

- An instruction specifies an operation and the locations of its data operands.

- A 32-bit word holds one encoded instruction.

- A sequence of instructions executed one after another constitutes a program.

- Both the program and its data are stored in the main memory.

Instruction Types:

- Load

- Store

- Operate

Processor Components:

- The program counter register holds the memory address of the instruction.

- The instruction register holds the current instructions.

- General-purpose registers hold data and addresses.

- Control circuits and the arithmetic and logic unit (ALU) fetch and execute instructions.

Program Counter (PC):

- As each instruction is fetched, the program counter increases its stored value by 1.

- After each instruction is fetched, the program counter points to the next instruction in the sequence.

- When the computer restarts or is reset, the program counter normally reverts to 0.

Handling I/O Devices:

An application program can:

- Read data from an input device.

- Write data to an output display screen.

- Sense the readiness of an input or output (I/O) device to perform a transfer.

Performance

How quickly can a program be executed?

Factors include:

- Speed of the electronic circuits in the processor.

- Access time to the cache and the main memory.

- Design of the instruction set.

- Number of operations that can be done at the same time.

Technology:

Improvements in transistor materials allow for faster execution of instructions.

Performance - Parallelism

Multicore Processors (across multiple cores):

- Multiple processing units can be fabricated on a single chip.

- Each of these processors is called a core.

- The term processor is used for a complete chip.

- There are various processors for chips, such as dual-core, quad-core, and octo-core.