Topic 3: Networks Flashcards
(31 cards)
Briefly describe a Local Area Network (LAN).
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. Computer systems interconnected with a LAN usually have high data-transfer rates between them.
Briefly describe a Wireless Local Area Network (WLAN)
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.
Can be less secure since potential intruders do not need a physical connection to the network.
Briefly describe a Virtual Local Area Network (VLAN)
A network configuration that separates a physical LAN into logical separate network. Even though all devices are connected to the same physical network, each logical separate network can not see the computer system or other shared resources of other logical separate networks.
Can be used when a business wants to separate the networks of its various departments.
Briefly describe a Wide Area Network (WAN)
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.
Briefly describe a Storage Area Network (SAN)
A SAN is a network that is created so that large storage devices can be accessible from servers in a convenient and easy way.
Briefly describe an extranet.
An extranet is a computer network that utilizes the Internet to allow controlled access by specific users to a specific LAN or WAN.
For example, a business may wish to securely share part of its network with suppliers, partners, or customers.
Briefly describe a virtual private network (VPN)
A computer network that connects two or more computer systems, but allows clients from remote locations to connect to the network through the internet as if they were physically present using a tunneling protocol to create a secure connection.
Briefly describe a personal area network (PAN)
A network that interconnects devices that are centered around an individual person’s workspace. Typically includes a mobile computer, smartphone, tablet that are interconnected through wired USB connections or wirelessly (typically through Bluetooth).
Briefly describe a peer-to-peer (P2P) network.
A network that does not utilize a client-server model where clients request resources and servers provide them. Instead, a P2P network uses a distributed network architecture where all the computer systems (called nodes or peers) are decentralized and are both clients and servers at the same time. Example: torrent filesharing
Outline the importance of standards in the construction of networks.
Standards are common rules shared between devices. Different hardware is made by different manufacturers. If there was not a common standard, these devices would not be able to communicate with each other.
Explain how communication over networks is broken down into different layers.
Network functionality is broken down into different layers. For example, the protocols that govern how data should be transmitted over a physical medium, and the protocols that govern how packets should be routed through a network.
The most-widely used networking standard is the Open Systems Interconnection model (OSI). It contains seven layers: Physical, Data link, network, transport, session, presentation, application. You do not need to understand the functioning of each layer, but you should be able to list two of the layers.
Explain the advantages of breaking down network communication into different layers.
Easier to manage, makes protocol design easier.
Manufacturers can focus on technologies of a particular layer.
Products of different manufacturers can work together.
Technology advances within a layer are independent of technology advances in a different layer.
Identify the technologies required to provide a VPN.
Internet access, VPN software (client software, utilities and server software) enabling private communication over the Internet, VPN routers and firewalls (to permit VPN traffic to pass), VPN appliances/server (to handle incoming VPN traffic), encryption/tunneling protocols to enable secure communication.
List the benfits of a VPN.
Companies can take advantage of the of the Internet to provide secure connections.
Employees can work as if they were directly connected to the company’s network.
Extends connections across numerous geographic sites.
Improves productivity of remote employees.
Improves security.
Reduces travel times and traveling costs for remote workers.
Explain how the use of a VPN has changed traditional working patterns.
Use of a VPN allows employees to work remotely from any geographic location. Enables employes to work from home.
Define the term protocol.
International rules that ensure the transfer of data between systems. A protocol that is recognized as the standard for a specific type of transfer is called standard protocol. For example: TCP/IP is a standard protocol
Define the term data packet.
Portion of a message that is transmitted through a network. Contains data such as check digits and destination address.
Explain why protocols are necessary.
Protocols can provide the following:
Data integrity: assurance that information has not been changed or corrupted during transmission.
Flow control: controlling the data flow rate to prevent the limited memory and bandwidth of networks from becoming overloaded.
Congestion: congestion happens when the request on the network resources exceeds the offered capacity. Protocols can help network devices manage this.
Error checking: the ability to check whether an error has occurred.
Explain why the speed of transmission can vary across a network.
Example factors that can affect the speed in the network:
1. Bandwidth of the network
2. Number of connected devices
3. Number of users and user demand at a particular time (traffic)
4. Packet loss and retransmission
5. Type of transmission media
6. Speed, technology and capacity of the network server
Define the term data compression.
The reduction of file size by encoding data using fewer bits.
Explain why compression of data is often necessary when transmitting data across a network.
Networks have limited bandwidth to transmit data. Compressing data reduces the amount of bits needed to represent the data meaning the time taken for it send over a network is reduced.
Outline the characteristics of different transmission media including speed; reliability; cost; security.
Metal conductor: cheap, middling bandwidth, reliable, very secure.
Fiber optic: very expensive, very high bandwidth, very reliable, extremely secure
Wireless: relatively cheap, high bandwidth (but lower than wired cables), low reliability (can be affected by factors like weather conditions, distance, topography), less secure.
Explain how data is transmitted by packet switching.
Data is organized in specially formatted units (data packets);
Each data packet contains: data, address of the sender, address of the receiver, size of packet, sequence number, control codes, etc.; which are routed from source to destination using network switches and routers;
network switches and routers determine how best to transfer the packet between a number of intermediate devices (routers and switches) on the path to its destination (rather than flowing directly over a single wire on the path to its destination);
data packets are reassembled at destination;
Outline advantages and disadvantages of a wireless network.
Advantages: don’t have to install cables which can often be expensive, is easy to set up a temporary link, costs less to set up a wirless network, easier to plan a wireless network, a lot of public access points exist, flexibility/convenience, is the only way to connect some devices (smartphones).
Disadvantages: gives relatively low speeds, gives high error rates, is affected by weather, offers weakest protection, security, privacy, less reliable, some old devices don’t have wireless capability
