Computer Networks, Hardware, Operating Systems, and Emerging Technologies Study Notes

What is a computer network?

Two or more computers, or other electronic devices, connected together so that they can exchange data.

What is the most common cable used to connect wired networks?

Ethernet cable.

What are the advantages of computer networks?

Files and documents can be sent and accessed immediately, they provide flexibility, central data storage is available, and physical hardware can easily be shared among many devices.

What are the disadvantages of computer networks?

They are initially expensive, viruses and malware can spread throughout the network, systems can be hacked, computer network crashes can cause loss of information, network management is difficult, and maintenance costs are high.

What is a Local Area Network (LAN)?

A private network belonging to an organization or business confined to one building or site, consisting of computers and devices connected to hubs and switches.

What are the disadvantages of a Local Area Network (LAN)?

Easier spread of viruses throughout the whole network, development of printer queues, loss of internet access if the main server goes down, security risks from stand-alone computers, and slower internet access.

What is a Wireless Local Area Network (WLAN)?

A network that provides wireless communication over fairly short distances using radio and infrared signals instead of cables, connecting via access points fixed into the wired network.

What is a Wide Area Network (WAN) and what connection technologies does it use?

A network extending over a large area, often created by joining several LANs together using a router or modem via optical fiber (glass) cables and satellite radio links.

What is a Personal Area Network (PAN) and what is a primary example?

A wireless networking technology designed for very short-range connections to eliminate the need for cables connecting a computer to other devices; an example is Bluetooth.

What is the function of a Network Interface Card (NIC)?

It connects to the motherboard to allow a device to connect to a network, converts binary data into electrical signals, and contains a permanent MAC address generated during manufacturing.

What is a Media Access Control (MAC) address and how is it structured?

A permanent address that uniquely identifies a device connected to a network, made up of $48\text{ bits}$ shown as six groups of hexadecimal digits ($\text{NN-NN-NN-DD-DD-DD}$), where the first letters show the manufacturer code and the second show the device serial number.

What are the differences between IPv4 and IPv6 addresses?

IPv4 is based on $32\text{ bits}$ (e.g., $254.25.28.77$), whereas IPv6 is a newer standard based on a $128\text{ bit}$ address (e.g., $\text{A8FB:7A88:FFF0:0FFF:3P21:2085:66FB:F0FA}$).

What four elements are contained in a data packet?

A header to identify the packet, the sender's IP address, the total number of packets making up the whole message, and the identity number of each packet.

Why is a switch considered an 'intelligent' version of a hub?

A hub broadcasts received packets to every connected device causing unnecessary traffic and reduced bandwidth, whereas a switch stores device MAC addresses and forwards data only to the matching port.

What is the purpose of a bridge in networking?

A bridge connects one LAN to another LAN that uses the same communication protocol, allowing different parts of a LAN to function as a single LAN.

How does a router determine where to send data packets?

It inspects the IP address of incoming packets and consults a routing table stored on the router's RAM to find the best shortest path to the destination.

What is data redundancy in cloud storage?

Storing data on more than one server in case of maintenance or repair, allowing clients continuous access to their data.

What is the difference between a public cloud and a private cloud?

In a public cloud, the customer and provider are different companies and it stores less sensitive data; in a private cloud, storage is dedicated behind a company firewall, the client and provider are integrated as a single entity, and confidential data is stored.

What are the two main sub-units of the Central Processing Unit (CPU)?

The Arithmetic Logic Unit (ALU), which carries out arithmetic and logical operations, and the Control Unit (CLU), which decodes, executes, and takes instructions.

How does Random Access Memory (RAM) differ from Read Only Memory (ROM)?

RAM is volatile temporary memory that can be read and written to for running applications and OS components; ROM is non-volatile permanent read-only memory containing startup code like the BIOS.

How do Hard Disk Drives (HDD) and Solid State Drives (SSD) compare?

HDDs are magnetic in nature, whereas SSDs use flash memory, are a more modern technology, and are replacing HDDs.

What is the role of a compiler versus a linker?

A compiler translates high-level code into machine code (object code), while a linker takes that object code and joins it with library routines to create a single executable program.

What is a device driver?

A program that allows a hardware peripheral device (such as a printer) to communicate with the operating system.

What is the difference between analogue and digital data?

Digital data consists of discrete, discontinuous values using only $1$ and $0$, whereas analogue data is physical data that changes smoothly from one value to the next