Topic 3 - Networks

Question 1

Server

Answer 1

A server can either be a computer system or a software application that provides a service to the other computer systems connected to the same network. For example, a server can provide the ability to the rest of the computers on the network to store and to share files, taking the role of a file server.

Question 2

Client

Answer 2

A client can either be a computer system or a software application that requests a service
from a server connected to the same network; For example, an email client software application can request from an email server software application to fetch any new emails that may have been received.

Question 3

Summary of client and server

Answer 3

a server computer system is a host running server software applications and
sharing its resources with clients that make requests. A client, on the other hand, does not share any of its resources but requests content from a server. Servers thus wait for incoming requests for content from clients.

Question 4

What are 3 most commonly used network components to connect two or more computer systems in order
to create a network?

Answer 4

Hub, Switch and Router

Question 5

Hub

Answer 5

A hub is the connection point for devices on a single network. Network devices and computer systems connect to a hub using Ethernet cables that attach to a port.
A hub consists of multiple ports. When a network device wishes to send data to some other device on the network, it sends the data to the hub. The hub then copies the data and sends it to all devices connected to its ports. The device waiting to
receive the data accepts the data. All the other devices just ignore it. Although passing the data along to every port ensures that it will reach its destination, a lot of traffic is generated on the network, since all the other ports that just ignore the data have to nevertheless
receive it. This slows down the network.

Question 6

Switch

Answer 6

A switch is also the connection point for multiple devices on a single network. However, unlike a hub, the switch can identify which network device is connected to which part. This allows the switch to transmit data to the exact port and network device for which it is intended. This means that when a network device wishes to send data to some other device on the network, it sends the data to the switch and the switch sends the data to the appropriate receiver rather than all the ports and devices connected to those ports. As such, networks connected with a switch are faster than networks connected with a hub.

Question 7

Router

Answer 7

A router is a more sophisticated device than both a hub and a switch. Its use is to join multiple networks and serve as an intermediary between these networks so that data can be exchanged effectively and efficiently between network devices of those networks. For example, a router is used to connect a home network to the Internet. A hub or switch would not be able to accomplish such a task in a simple manner.

Question 8

What are some network types?

Answer 8

Local Area Network (LAN)
Wireless Local Area Network (WLAN)
Virtual Local Area Network (VLAN)
Wide Area Network (WAN)
Storage Area Network (SAN)
Internet
Extranet
Virtual Private Network (VPN)
Personal Area Network (PAN)
Peer-To-Peer (P2P)

Question 9

Local Area Network (LAN)

Answer 9

LAN is a computer network that connects computer systems that are within a limited geographical area such as a room, a home, an office building or a school.
LANs allow the sharing of peripheral devices between the connected computer networks.

Question 10

Wireless Local Area Network (WLAN)

Answer 10

A WLAN links two or more computer systems within a limited geographical area, similar to LAN. The difference from a LAN is that WLAN devices are connected using some sort of wireless connection method. This allows users to have mobile devices and laptops connected to the network and be able to move around.
WLANs have all the benefits of LANs, as well as the ease of wireless connection that allows
the use of mobile devices on the move. However, WLANs can be less secure than wired LANs since a potential intruder does not require having a physical connection to the network.

Question 11

What are some Similarities and Differences between LAN and WLAN?

Answer 11

Similarities: Both act on a local level; Both allow communication; Both used to connect devices; Both allow sharing resources

Differences: They use different transmission medium; A LAN is safer; The LAN is faster; WLANs offer greater flexibility

Question 12

Virtual Local Area Network (VLAN)

Answer 12

A VLAN can be used to partition the initial LAN, where every department is
connected, into logical separate networks. Each logical separate network cannot see the
computer systems or the shared resources of other such logical separate networks, without
specific set up that allows it to see them.

Question 13

What are some Similarities and Differences between LAN and VLAN?

Answer 13

Similarities: Both act on a local level; They both have the same attributes, Both allow communication; Both used to connect devices; Both allow sharing resources.

Differences: VLAN delivers better performance and is safer; The formation of virtual workgroups is easy; VLANs offer greater flexibility. Even if someone who is using laptop moves to another place he/she will remain in his/her dedicated VLAN; The partitioning of resources is easier; VLANs are independent on the medium and the physical topology of the network; Sometimes the management/administration of a VLAN is complex.

Question 14

Wide Area Network (WAN)

Answer 14

WAN is a computer network that connects computer systems that are within a large
geographical area. The most obvious example of a WAN is the Internet. A WAN covers a
broad area, such as a city, a country or even a network of countries allowing individuals,
businesses and governments to carry out their daily business regardless of location. A WAN typically consists of LANs connected together over a broad geographical area.

Question 15

What are differences between LAN and WAN?

Answer 15

A LAN is faster; A WAN is more expensive; LAN is easier to maintain than Wan; LAN serves local area while WAN serves large geographical areas.

Question 16

Storage Area Network (SAN)

Answer 16

A SAN is a network that is created so that large storage devices can be accessible from servers in a convenient and easy way.

Question 17

Intranet

Answer 17

An “intranet” is the broad term for a collection of private computer networks within a company, a school or an organization that utilizes standard network protocols like TCP/IP. It could be considered as a private analogy of the Internet. Its main purpose is to facilitate communication between individuals or work groups and to improve data sharing. Intranet resources and services are not available to the world outside the company. In all cases where an intranet is connected to the internet, a firewall is used for protection.

Question 18

Internet

Answer 18

The Internet is a global WAN connecting millions of computer systems. Since it is a WAN, the Internet connects a large number of smaller networks together, thereby creating the largest WAN network used by billions of users worldwide.
The Internet provides an extensive number of
services to users such as the World Wide Web
(WWW), which consists of websites and webpages, as well as support for email, file
transfer and other services. As such the Internet is not the same as the WWW but rather the WWW is a service of the Internet.

Question 19

Extranet

Answer 19

An extranet is a computer network that utilizes the Internet to allow controlled access by specific users to a specific LAN or WAN.

Question 20

Virtual Private Network (VPN)

Answer 20

VPNs are primarily used for remote access to a private network. For example, employees at a branch office could use a VPN to connect to the main office’s internal network. Alternatively, a remote worker, who may be working from home, could need to connect to their company’s internet or restricted applications.

Question 21

What are similarities and differences between VPN and EXTRANET.

Answer 21

Similarities: both use the internet; They are both considered inexpensive solutions; They both provide some security.
Differences: A VPN provides a secure connection to employees of the company, while an extranet limits access to the company network to selected (authenticated) outsiders; VPN provides more security (data send and received always encrypted).

Question 22

What are the differences between LAN and PAN?

Answer 22

A LAN connects computers and devices that belong to different people, while 3 PAN suits the needs of a single person.
A PAN operates on a smaller area than a LAN.
A PAN does not require a device such as a hub or switch. USB and Bluetooth technologies are used instead.

Question 23

Persona/Area Network (PAN)

Answer 23

PAN is a network that interconnects devices
that are centered around an individual
person’s workspace. It can be understood as a LAN that supports only one person, instead of a group of people, and covers a very short range, a maximum of 10 meters. An example of a typical PAN would involve a mobile computer, a smartphone and a tablet all interconnected and sharing data such as
emails, calendars, photographs, etc. Devices
on PANs can connect both wired (typically through USB) and wirelessly (typically through
Bluetooth) depending on the technologies used.

Question 24

Peer-To-Peer (P2P)

Answer 24

P2P is a network that does not utilize the client/server model where client request
resources and servers provide them. Instead, a P2P network uses a distributed network
architecture where all the computer systems (called nodes or peers) in the network are
decentralized and are both clients and servers at the same time, consuming and supplying resources from and to the other computer systems connected to the network.

Question 25

Which are organizations standardize networking protocols?

Answer 25

There are two organizations standardize networking protocols: Institute of Electrical and Electronics Engineers (IEEE) and Internet Engineering Task Force (IETF).

Question 26

Advantages of layers

Answer 26

Easy to manage;
Greater understanding of each layer;
Common language for each layer;
Makes protocol design easier;
A manufacturer can focus on technologies of a particular layer;
Products of different manufacturers can work together;
Technology advances of a layer are independent of technology advancements of
other layers (wireless technology advances are not dependent on advances of media format compression (GIF))

Question 27

OSI (reference model)

Answer 27

The most—widely used networking standard is the Open Systems Interconnection model
(OSI). The OSI Model was established by the International Standards Organization (ISO) and aims to facilitate communication across a variety of systems. It contains seven layers.

Question 28

OSI Model layers

Answer 28

1. Application: Performs various services for the applications used by the end users. Example protocol: HyperText Transfer Protocol (HTTP)
2. Presentation: Provides data format information, data compression information and data encryption information to the application. Example protocol: Portable Network Graphics (PNG).
3. Sessions: Manages sessions between two users. Example protocol: UNIX X Window system core protocol.
4. Transport: End to end connections (hosts). Definition of data segments –> assignment of numbers –> data transfer –> reassemblage of data at the destination. Example protocol: TCP.
5. Network: Héndles routing of packets across a network through intermediary devices. Example protocol: IP.
6. Data link: Error handling of physical transmission. Builds frames and amends transmission rate according the buffer of the receiver (flow control). Example protocol: Ethernet, HDLC.
7. Physical: Transmits 0s and 1s over media between devices. Definition of media
   specifications. Voltage levels. Example protocol: R8232-C (serial port).

Question 29

Virtual Private Network

Answer 29

It uses the internet to allow people to log into a network
remotely and access its resources, but encrypts the connection to thwart eavesdroppers.
* If your company sets you up with a VPN, you can access your corporate intranet, file servers or email from home or a coffee shop – just as if you were using it in your office.
* This makes VPN a popular way to support remote workers, especially in fields where privacy is paramount, such as health care.

Question 30

What are benefits of VPN?

Answer 30

Communication is easier; Companies take advantage of the Internet to provide secure connections; Decreases operational costs versus traditional WAN; Improves overall productivity and security; Offers flexibility.