Wired and Wireless Networks Flashcards
What is a network?
Two or more computing devices connected together in order to share resources
What is a Local Area Network?
Two or more computing devices that are connected together in a close geographical area
What is a Wide Area Network?
Connects two or more LANs that are in different geographical locations
What is a node?
Any device that can connect to a network
What is a workstation?
A computer that is part of a network
What do devices on a LAN usually connect with?
Ethernet cables or Wi-Fi
Give three reasons why networks are commonly used
- Resources and files can be shared by users on a network
- Users can log on to any workstation on the network and still access their files
- Backups of files and documents can be made centrally rather than backing up each machine individually
Give three downsides of using computer networks
- They are expensive to set up and maintain as they need expensive copper cables and/or Wi-Fi to connect the nodes together
- If their is a problem with the central file server then no one will be able to access their files
- Viruses and malware can quickly spread throughout the network if security measures are insufficient
Name three different methods of connecting WANs
Fibre optic cables, satellite communication links and microwave links
Give three reasons why WANs are commonly used
- They enable LANs to connect to one another
- They allow workers to collaborate even if they are in different geographical location
- They allow files and data to be shared between LANs
Give two downsides of using WANs
- It is expensive to hire a WAN service from a telecom operator
- If there is a failure, it can be more difficult to solve the issue as the company itself does not own all parts of the WAN
What is network performance?
How well data is transmitted through the network
What is bit rate?
How the speed of the network is measured
What is bandwidth?
The amount of data that can be transferred over a connection in a given period of time
What is contention ratio?
The ratio of number of users compared to the bandwidth available
What is transmission media?
The technologies used to carry data around a network
What is error rate?
How many errors in the transmission of data occur over a given period of time
What is latency?
The amount of time it takes for a packet of data to travel across the network
What is a high latency network?
A network with long or significant delays
What are the five factors which affect the performance of a network?
Bandwidth, latency, error rate, transmission media and the number of users on the network
How does a Wi-Fi network makes use of frequency bands and channels?
Wi-Fi works in two frequency bands, one at 2.4GHz and the other at 5GHz. These are further divided into channels.
Why are separate channels a good idea for Wi-Fi networks?
Separate channels help to reduce the interference caused by other nearby devices
What are the four factors which might affect the performance of a Wi-Fi network?
Radio interference, physical obstacles, distance, channel availability
What is architecture?
The layout of a network, or how a network is organised
What is a client server network?
A type of network managed by a server which takes requests from client devices
What is a server?
A specialist computer on a network which provides services for other devices eg. file storage, web pages and printer access
What is authentication?
Using a network ID and password to check the authenticity of a user who is attempting to log into a network
What is a shared drive/area?
A file storage area on a network server where users can access files and resources
What are access rights?
The network manager will assign a certain level of permission to your account. These will govern which resources or folders you are able to view, open and amend.
What do computers on a client-server network connect to the server through?
A central hub or switch
What are three advantages of a client-server network?
- You can log in from any workstation
- Backups can be performed centrally
- Software can be installed and updated centrally
What are three disadvantages of a client-server network?
- The equipment is expensive to set up and IT specialists are needed to maintain the network and server
- If the server goes down all clients loose access to their work
- The server may become overloaded if too many clients are accessing it at once
What is the role of a Network Interface Card?
The NIC converts data going out from a networked device into a format that is compatible with the network
What is a MAC address?
Every NIC has a unique number hardwired or ‘burned’ into it. This is called a Media Access Control Address. Every device on a NIC and each NIC has its own MAC address. Therefore, every device on the network can be identified.
What are two disadvantages of hubs?
- Because hubs send the data to every port and each device there is a lot of data being transmitted around a network. This can lead to data collisions where the data has to be resent which slows down the performance of the network.
- They are not very secure as every device on the network can view the data whether it is intended for them or not.
Explain why a switch is often preferable to a hub
Both link nodes to one another in order to exchange data however switches only transmit data packets to the intended nod. Therefore switches have fewer data collisions and improved security.
What is the role of a Wireless Access Point in a network?
A WAP is used to connect Wi-Fi devices to a wired network without the need for physical cables. The WAP picks up data packets and converts them into a format suitable for the wired network and vice versa.
What is a disadvantage of using WAPs in a network?
WAPs don’t read the destination address of the data packets so they broadcast the data to every device connected. This can result in security issues as anyone else using the Wi-Fi network could read your personal data.
Compare ethernet cables and fibre optic cables
- Ethernet cables are copper wires enclosed in a plastic sleeve. Fibre optic cables have a glass or plastic core
- Ethernet cables transmit data using electric signals. Fibre optic cables transmit data using light.
- Ethernet cables carry less data than fibre optic cables.
- Fibre optic cables are more expensive than ethernet cables.
Explain how a router sends data packets
When a data packet arrives at the router, the router reads the data packet’s destination IP address. The router uses a database to look up where that IP address is located. It then determines all of the different paths or routes it can use to send the data packets through in order to reach the IP address. It also checks how busy each path/route is at that very moment and then sends the data packets via the fastest path.
What is the role of an Internet Service Provider?
An ISP is a company that provides internet access by charging a monthly fee
What is a URL?
A uniform resource locator eg www.google.com is a unique web address for every webpage on the internet
What is an IP address?
It’s a unique number which every devices connected to a WAN or the internet has and allows for each device to be identified and located
What does IP stand for?
Internet Protocol
How is an IP address stored?
It is stored as a denary number with each digit between 0 and 255. It contains four numbers separated by dots.
What is meant by a static IP address?
It is permanent
What is meant by a dynamic IP address?
It’s temporary and changes each time the device accesses the internet
Is the IP address assigned through hardware or software?
Software
What is the Domain Name System?
It acts as a directory of every domain name and it’s corresponding IP address
How does the DNS work?
Once you’ve typed in the name of the name of the website or web page you wish to visit, your browser makes contact with the DNS server. The server contains a database that matches the domain name up with it’s registered IP address. The DNS sends this information back to your computer. Your computer then attaches the IP address to the data packet to be sent. The data packet travels over the internet to its destination. The server where the website is stored then sends back the data which was requested.
What are the advantages of the DNS?
- You don’t need to remember any IP addresses of websites
- So long as you are connected to a DNS server you can access any website for which there is a stored IP address
What would happen if the DNS server didn’t have a record of the IP address for your website?
The DNS server would contact other DNS servers to interrogate their records
What is local hosting?
Where you host your own website on your own PC by setting it up as a server and allowing others to connect to it and access web files stored on your server
Why might someone decide to host their website locally?
Because it is less expensive and it gives them full control of their own website
What are three issues of local hosting?
- Your computer needs to be always on
- If lots of people are trying to access your server, you might not have enough bandwidth
- It can be difficult to protect a website from deliberate intrusion attempts and malware
What is external hosting?
Where you pay a web hosting company to host your website on their server
Why might someone decide to host their website externally?
- They don’t have to worry about bandwidth
- They don’t have to worry about viruses or malware
- The people who own the server will maintain it to make sure that it’s always on
What is a shared web hosting service?
A server which has multiple websites hosted on it
What are the benefits of using a shared web hosting service?
- It’s cheaper
- You don’t have to worry about bandwidth
What are the limitations of using a shared web hosting service?
- Because all users share bandwidth, CPU time and RAM if one of the websites is a heavy user of resources then the performance of the other sites can suffer
- You may not be allowed to install specific modules or scripts that you want to run on your sight
What is a dedicated hosting service?
A server which only hosts one website
What are the benefits of a dedicated hosting service?
It is faster as the whole bandwidth is available for one website
What are the limitations of a dedicated hosting service?
It’s expensive
What is a virtual server?
A powerful server that runs specialist software allowing it to create many ‘virtual servers’ within itself. They are then rented out to customers to host their websites.
What are the benefits of a virtual server?
It is cheaper as the server is shared
What is ‘the cloud’?
A range of services that are run on the internet
Give three examples of services that are available in the cloud
Online storage, online backups, streaming services
What is a virtual network?
Virtual networks make use of software to divide devices on a LAN into smaller groups
Give three reasons why setting up a virtual local area network may be useful
- There is improved security as if one VLAN is compromised, because the others are partitioned, they will not be affected
- A virtual network is flexible as it is easy to remove computers from the VLAN using software, there is no need to add extra cables
- It is easier to install software needed by specific groups of people
What is a virtual private network?
It is used to connect devices to a LAN through a WAN. A VPN allows external devices to exchange data with a network using an encrypted connection.
Why might a VPN be more useful for an international company?
Users can log into the company network from anywhere with an internet connection. It is much more secure than just communicating openly over the internet. It is also much cheaper than maintaining a company-wide WAN.
