Networks Flashcards
(116 cards)
1
Q
What is a network?
A
A computer network is two or more computing devices (such as a computer) connected together in order to share resources and exchange information.
2
Q
What is a device that is able to join a network?
A
A device is said to be ‘network enabled’ when it is capable of joining a network.
3
Q
Example of a network enable devices?
A
Network enabled devices include
Network servers
Personal computers
Tablets
Smart phones
E-readers
Smart televisions
Printers
4
Q
What are the two types of networks?
A
There are two types of networks that you need to understand, Local Area Networks (LANs) and Wide Area Networks (WANs).
5
Q
What is a LAN?
A
A Local Area Network is one that has two or more network-enabled devices connected within a fairly close geographical area.
6
Q
What are some examples of places you will find LANs?
A
For example the LAN may be located within a single building such as a home or business office or it may cover a few nearby buildings as well, such as an University campus, hospital, library or school.
7
Q
How can devices be connected on a LAN?
A
Computers and devices can be connected by physical Ethernet cables, which are usually owned by the organisation. They can also be connected wirelessly by using Wi-Fi connections.
8
Q
What are advantages of using a LAN?
A
- A user can log on from any workstation and still access all of their files.
- Peripherals such as printers and photocopiers can be shared between many users, thus reducing costs
- Resources and files can be shared by users, this means that they can collaborate on a project.
- Backups of files and documents can be done centrally rather than needing to do it from each machine
- When software needs to be installed it can be done centrally rather than having to go to each individual workstation.
- An anti-virus and malware check can be carried out from the server to all workstations.
- Data can be transmitted very quickly between networked computers
- A LAN at home allows many devices to connect to one another, such as a smart TV or a media server
9
Q
What are the disadvantages of using a LAN?
A
- Network failure. If there is a problem with the file server then no one will be able to access their files. If the internet server has an issue no one will be able to get onto the internet.
- Slow service. If there are a lot of users logged into the network requesting files and jobs then the network can start to slow down. There is only a limited amount of bandwidth in any network and the more data that is being used the slower things will become.
- Viruses and malware. Although these are dealt with centrally, if someone does install a virus on the local workstation it could easily spread
around the network - Cost - large business networks can be expensive to set up and keep running. The cost
of the physical components can be very high.
-Expert support required. Many business networks will require specialist staff such as network managers or technicians who can deal with problems as they arise and keep the network running smoothly.
- Security. Although users have their own user names, giving them access to just their files, users can be careless and not log out when they leave their workstation. This could give an unauthorised person access to their files or to sensitive documents stored centrally on the network.
10
Q
How to improve the security on a LAN?
A
- Passwords. Strong passwords should be required and users encouraged to change their passwords frequently - at least once per month.
Access rights. Each user is assigned to a group e.g. students, teachers, admin etc. This is done via the user name. Each group is given different permissions to view folders and files. For example, when students log in they cannot see all of the admin and finance documents whereas office staff cannot view students’ work. - Access rights can also govern what you can do on a network, for example, install software, delete files etc.
- Audit log. This means the computer will record every important event in an ‘audit file. It records who saved what and when. Who deleted records or changed them.
- Backups. Central backups should be made regularly, at a minimum once a day. This way a rollback or restore of files can be made if an issue occurs.
- Encryption. Data travelling around the network should be encrypted, especially if hubs and Wi-Fi are being used. This is because data is broadcast to all devices on the network.
- Installing software. Users should not be able to install software or run .exe files because of the risk of introducing malware and viruses into the network.
11
Q
What is WAN?
A
A wide area network (WAN) connects two or more local area networks (LAN) that are in different geographical locations.
12
Q
What are some examples of WANs?
A
For example, a company might have offices in London and also New York, but they want to share a common work area so they can collaborate. In this case the LAN in London is connected to the LAN in New York by a Wide Area Network.
A WAN can also connect offices that are a bit closer together, such as estate agent offices in different towns. In this case a ‘leased line’ from a telecom company can be used.
13
Q
How are WANs usually set up?
A
A company normally hires the WAN from a major telecom company because it is so expensive and complicated to set up and maintain.
14
Q
How may WANs be connected?
A
The WAN involves long distance communications and this can be achieved using
- Fibre optic lines, including laying undersea cables
- Satellite communication links
- Leased telephone lines
- Microwave links
15
Q
What is largest WAN that exists?
A
The largest WAN of all is of course the internet. No single organisation owns the internet itself.
16
Q
What are the pros to using a WAN?
A
- Allows LANs to connect to one another.
- Allows workers to collaborate over a wide area, even across continents..
- Allows files and data to be shared between LANs. A WAN also allows direct person-to-person contact by methods such video conference virtually anywhere across the planet.
17
Q
What are the cons of using a WAN?
A
-Can be expensive to hire a WAN service from the telecom operator.
- With a LAN, a company often has its own experts to maintain the network so any problems which arise can be addressed quickly. However with a WAN, it is owned by a number of external suppliers and so a failure of the WAN is usually beyond the control of the company to fix. For example, when an external DNS server fails, this immediately affects web access in the company.
18
Q
What is bandwidth?
A
Any network has a limit in how much data can be moved across it in a given time. This quantity is called the bandwidth of the network.
19
Q
What is bandwidth measured?
A
Bandwidth is measured in bits per second also called the bit rate.
Typical bit rates are:
Kilobits per second (Kbps), a thousand bits per second.
Megabits per second (Mbps), a million bits per second.
Gigabits per second (Gbps), a thousand million bits per second.
20
Q
What happens as the bandwidth becomes higher?
A
The higher the bandwidth the more expensive the network becomes to put together because of the cost of the cables and equipment.
21
Q
What happens if there are more users of the network?
A
Even the most impressive network can be slowed down if too many people are using it at the same time because the bandwidth has to be shared between all users. The more bandwidth each person uses, the less is available for everyone else.
22
Q
What is the limit of users in a network?
A
In a wired network the maximum number of people that can connect is simply the number of workstations connected to the network. However, this does not mean that bandwidth is shared equally amongst them.
23
Q
In a Wifi network what is the limit of users in a network?
A
In a Wi-Fi network the same thing applies - the more people or devices connecting to the network the slower the performance becomes.
There is also a limit in how many connections a Wi-Fi WAP accepts at any given time.
24
Q
What are transmission media?
A
These are the physical cables used within the network. They too have a performance limit in terms of bandwidth and allowed cable lengths.
25
What is a popular choice for a wired network?
A very popular choice for a wired network is copper Ethernet cables to carry data.
They have a length limit because the signal gets weaker and weaker the more it has to travel along the cable. Eventually it becomes too weak to be useful.
26
What are the two main performance categories for ethernet cables?
Ethernet cables come in two main performance categories called Cat-5 (slower) and Cat-6 (faster).
27
Why would pick the Cat-5 cable or Cat-6 cable?
Cat-5 cable is cheaper per metre and is an excellent choice for a 100Mbps network. However, if a 1Gbps network or higher is required then the more expensive Cat-6 cable is recommended.
28
How do fibre optic cables transmit data?
Fibre optic cables transfer data using light which is reflected along the inside of the cable. Fibre optic offers extremely high bandwidth - in fact the bandwidth is actually limited by the equipment connected to it rather than the cable itself. But fibre optic is expensive compared to standard ethernet copper cable.
29
When is copper cable or fibre optic cable used?
Many of the larger networks use both types - copper cable for local connections and a high-bandwidth fibre optic cable to handle the heaviest traffic such as between two LANS
30
What the four different ways Wi-Fi performance can be affected?
- Range
- Radio interference
- Blocked by walls and floors
- Limited connections
31
How do errors in a network effect performance?
A factor in measuring network performance is how many data errors happen over a given time.
An 'error' happens when a binary 1 was sent, but a binary 0 was actually received or the other way around.
32
How do errors happen?
There are two main reasons for errors happening:
- Interference
- Signal is too weak
If a cable or switch is too near heavy equipment such as electric motors or other power equipment then interference may cause bits to flip randomly. This is why shielded cables are used to try and reduce this problem, and network cable run layouts are thought through carefully to avoid problems.
The other factor is length of cable - the longer the cable, the weaker the signal. For example the longest recommended length of Cat-5 cable is 100 meters. If the signal gets too weak, then errors begin to creep in.
On a wireless network, radio interference can introduce errors. And if the Wi-Fi signal is too weak, then again errors creep in.
33
What is another factor of network performance?
On a small local area network, latency is not much of a problem as everything is quite close to one another.
But on large networks such as a WAN (e.g the Internet), latency becomes much more important.
34
How does latency happen?
Every switch, cable and router is adding delay (latency) to the connection. And to make it worse, the actual connection changes second by second as the routers decide which path to use at that instant. This will cause bits to arrive in a different order to what was sent.
A high performance network should have low latency.
35
What are wired networks affected by?
Performance of wired networks is affected by:
Type of cable connection (Ethernet or fibre optic)
Bandwidth available
Number of users
Error rates
Latency
36
What are wireless networks affected by?
Performance of wireless (wi-fi) networks is affected by:
The number of connections available
Range from WAP
Radio interference
Physical layout; solid walls and floors block signals
37
What are some pros of a wired network?
- Allows hundreds of people to log in at the same time.
- It is immune to radio interference
- High bandwidth, more than 10 Gbps is common
- Excellent security as a computer needs to be physically connected to the network
- Not affected by building layout
38
What are some cons of using a wired network?
- It is more costly than Wi-Fi to install in a building.
- Not portable as each computer needs to have a network socket available.
39
What are some pros of using a wireless network?
- Only needs a Wireless Access Point to set up, so is cheaper.
- Very mobile, an user can carry their laptop from office to office and not lose a connection.
40
What are some cons of using a wireless network?
- Can only allow a limited number of people to connect at any one time
- Affected by radio interference
- Lower bandwidth
- Not so secure as connection is by radio. So the WAP needs a strong password and encryption to disguise data being transmitted
- Signal is affected by walls and floors
41
What are the two main ways a LAN can connect nodes?
Client-Server
Peer-to-Peer
42
What is a Client Server network?
In a Client-Server LAN arrangement, most files and data are stored on a server. All computers on the network connect to this server through a central hub or switch.
The other computers on the network are called 'workstations' or 'clients'.
Users can access files and data from the server using any workstation. They just need to log into their account using their username and password. These accounts are managed by the server. Once they log in, they will see their work area or 'desktop' appear on the workstation screen.
Workstations cannot normally 'see' or share data with each other directly over the network. If people need to share data then a 'shared network folder' is created on the server by the network manager in order to share files.
There may be multiple shared folders on a server with different access rights.
43
In a Client-Server LAN what special features are there?
Users will have their own private area on the network where they can save their files and documents. No one else can access this area (except the network manager and staff).`
A client server network requires a specialist network operating system.
As files are stored on the server and they can be backed up centrally.
44
What is a Peer-to-Peer (P2P) network?
Peer to peer networks are very common in small offices or at home where there are only a few computers connected together.
With a peer-to-peer network a central server is not required because the files are stored on the hard disks of individual network machines.
Each computer on the network has equal importance and no more privileges than any other.
Each computer is both a client and a server - it acts as a 'host'. And users can access files and peripherals directly from all the other peers on the network.
Each peer computer can be set up to share folders with other peers.
45
What are the differences between a Client-Server and a P2P network?
[CS] = It has one or more servers
[P2P] = There is no central server
[CS] = A workstation computer or 'client' is used to log in to the server
[P2P] = Each peer may have its own local user accounts (or just a single account)
[CS] = The network administrator sets up shared folders on the server
[P2P] = Each peer can be set to share folders (or no folders at all)
[CS] = Needs technical skill to maintain a client-server network
[P2P] = Needs little technical skill as operating systems such as Windows and Linux have built-in support of network sharing
46
What are the differences between a Client-Server and a P2P network?
[CS] = Files and data are stored centrally on the server
[P2P] = Files and data are stored locally or in a shared folder hosted by a specific peer computer
[CS] = A broken workstation has no effect on the overall network. You just log in to a different workstation. A broken server, though, takes down the entire network.
[P2P] = A broken or disconnected peer computer has an effect on all peers because their shared folder(s) are no longer available.
[CS] = Commonly used in organisations that need to connect many workstations / computers together e.g. school network.
[P2P] = Commonly used in small LANs such as at home or a small office with few computers
[CS] = Requires a network operating system
[P2P] = Can use a standard operating system
47
What are the pros to a Client-Server?
- With a single central server, files can be backed up more easily
- Installation of new software to the network is easier and faster
- Software only has to be licensed to the server itself
- Client machines (workstations) do not need much software or file storage of their own.
- Simpler to manage security and permissions for large networks
48
What are the cons to a Client-Server?
- Expensive to set up and needs IT specialist to maintain the network and server
- Server dependence - if the server goes down all clients lose access to their work
- The server may become overloaded if too many clients are accessing it at once
49
What are the pros to a (P2P) network?
- No single central point of failure. If one peer goes down, the others can continue to function.
- Easier to manage with small networks, for example two or three computers in a small office
50
What are the cons to a P2P network?
- No centralised management - security and updates installed separately + backups are more complicated
- Copying files between devices creates duplicates so it's easy to lose track of what's stored where and which are up to date
- Peer machines are less reliable and data may be lost if one fails
- Machines are prone to slow down when other devices access them
51
What is a NIC?
Networks need a method of telling connected devices apart from one another. The most commonly used method is the Network Interface Card (NIC).
This is an electronic chip built into the motherboard of the device. It is hard-wired with a unique 'address', called a Media Access Control address (or MAC address).
No two MAC addresses are the same. So networks can use them to uniquely identify the connected devices.
52
What does the NIC do?
In addition to holding the MAC address, the NIC is responsible for converting data on the computer into the format used by the network, and vice versa. Each network has its own set of rules, called a network protocol, and it's the NIC's job to ensure that the connected device follows these rules.
53
What are hubs?
Hubs are a piece of hardware used to connect computers on the same network together. Every device gets plugged into the hub via cables. The hub has a socket, or 'port' available for each device. Larger networks might need a bigger hub with more ports.
54
What do hubs do/
To communicate across the network, devices send data in chunks called 'packets'. When a hub receives a data packet from any computer, it immediately copies it and broadcasts it to all connected devices. The packet includes a destination address, so the receiving computer knows to open it and all other computers discard it.
This is a cheap and effective way of transmitting data, but it is a little inefficient. Even if the data is meant to go to only a single computer, the hub will send it to all of them at once.
55
What some issues with hubs?
- Data collisions are more likely to happen with hubs sending data to all devices
- Using a hub to connect a network can be a security problem.
This is because when a hub receives data it will forward it to every device it connects to, regardless of whether the data was only meant to be sent to just one. This means that there is the potential for any computer connected to the hub to read data that was not intended for it.
56
How can data collisions slow down the network?
So if two or more computers want to place a data packet on to the network at exactly the same time, then a 'data collision' will take place. If this happens, the collided data is marked as unusable and the two computers are forced to send their data packets again, at slightly different times.
This is fine for a network with only a few computers. You will not notice the small delay caused by data collisions.
But imagine what happens when a hundred PCs are sharing the same network and they are all wanting to send their data packets. This will most likely result in thousands of data collisions per second - each one costing a small amount of time. You will certainly notice the network 'slowing down'.
57
What is a switch?
A switch looks the same as a hub externally but the way it works is different. Unlike a hub, it does not broadcast every data packet to every device which means there is improved security.
58
What are benefits of a switch?
It does not broadcast every data packet to every device which means there is improved security. It knows which port is connected to the destination device by its MAC address and so it only sends the data packet to that port alone. This makes it more secure than a hub.
Switches also reduce the impact of data collisions and so help speed up the running of the network.
59
What are cons of using a switch?
On the other hand, a switch is more expensive than a simple hub. So it tends to be used in high bandwidth, high performance networks.
60
What are some difference between the hub and switch?
- A hub connects nodes on the network together. It is not intelligent yet a switch is an intelligent device which connects nodes on the network together
- Higher risk of data collisions leading to slower network performance yet with switches it has a lesser risk of data collisions leading to improved network performance
61
What is a router?
A router is a device that transfers data packets, by the most efficient route, from one network to another i.e. between networks.
62
What does a router do when a data packet arrives?
When a data packet arrives, the router does the following:-
Reads the data packet's destination address
Looks up all the paths it has available to get to that address
Checks on how busy each path is at the moment
Sends the packet along the least congested (fastest) path
63
What are some other functions a router?
Other tasks the router can perform:
Exchange protocol information across networks
Filter traffic - helps prevent unauthorised intrusion by malware
You are probably familiar with a home router, such as the one shown below. This connects a home network to the largest network of all - the internet.
64
What is a Ethernet cable?
An ethernet cable is made up of a set of four 'twisted pair' copper wires enclosed in a plastic sleeve with a standard network plug on the end. This is done to reduce internal interference.
Data is carried through the cables by means of electrical signals.
65
What is a fibre optic cable?
Fibre optic cables are made up of many glass fibres held together inside a sheath. They use light signals to transport the data, often over a long distance.
Fibre-optic cables can be used to connect two or more local area networks, for example, two buildings on an university campus.
Also, it doesn't suffer from interference and can transmit over long distances without loss of signal quality
The downside of this technology is that fibre optic cable is a lot more expensive than Ethernet cable.
66
What is a WAP?
If you want to connect Wi-Fi devices to a wired network, you need a wireless access point (WAP).
67
How do WAPs work?
If you want to connect Wi-Fi devices to a wired network, you need a wireless access point (WAP).
The WAP has a cable connecting it to the network hub or switch.
A WAP is able to pick up Wi-Fi data packets and convert them into data packets for the wired network, and also the other way around - wired data packets back into Wi-Fi packets.
A WAP is similar to a hub in that it does not read the destination MAC address of a data packet and so the data is broadcast to everyone connected to it.
68
What are some benefits of the WAP?
Wireless technolgy makes it easy for people to access a network and transmit data without being physically connected i.e. with wires. It gives people freedom of movement wherever the Wi-Fi signal is available.
Extra nodes can easily be added enabling more people to use the network. And unlike a wired network, no building work is required to add those extra nodes i.e. no holes need to be drilled in walls for cables.
WAPs are very commonly found in public areas such as airports, cafes and offices.
69
What are the cons of a WAP?
This is why it is a bad idea to connect to a sensitive web site such as your bank or savings site as all your data packets can potentially be read by another computer connected to the same wireless access point.
70
What is network topology?
This is a technical term that describes the layout of connections in a network.
71
What is each device within a network called?
Each device within a network is called a 'node'. A node could be a workstation, a printer, a server etc.
Each of these nodes is connected to other nodes either by cable or Wi-Fi.
72
What are some different network topologies?
There are a number of different network topologies (layouts) for example, bus, ring, star and mesh. However for the OCR syllabus you only need to know about the star and mesh topologies.
73
What is a star topolgy?
The star network topology has a central device directly connected to all other nodes. Just like a star shape.
The central node could be a hub, a switch or a server.
74
What are uses of a star network?
The star network topology has a central device directly connected to all other nodes. Just like a star shape.
The central node could be a hub, a switch or a server.
75
What are the advantages of a star topology?
- Star networks are very reliable. If one connection fails, it does not affect other users
- Very few data collisions as each node has its own cable to the server
- Good security - no workstation can interact with another without going through the server first
- Simple to add or remove a node as it has no effect on any other node
- Scalability - can add many new nodes.
76
What are the disadvantages?
- The most expensive network layout to install because of the amount of cables needed
Installing the network usually needs experts to set it up
- Extra hardware such as hubs and switches may be needed
- If the central switch or server fails, the whole network is down
- Requires a high performance switch or server in the centre as all traffic passes through it.
77
What is mesh network?
In a mesh network, each node relays the data it receives to other nodes within reach. Unlike a star network, there is no central node in a mesh network.
Peripherals such as a printer needs to be connected to a workstation or server and be in 'share' mode. This means other workstations can see the printer listed as available for use. If the server connected to the printer is switched off or offline, then so it the printer.
78
How are the nodes connected in a mesh network?
Using cables to connect the nodes means that a wired mesh network would rapidly become too expensive and complicated. However, when the connections are wireless, a mesh network offers significant advantages over a star topology.
79
What are the advantages of a mesh network?
Very robust network. If one path fails, the rest can still be used
There is no central node to fail
Excellent for wireless networks as each node re-broadcasts all the data packets it receives.
It can handle very high data traffic rates
Data packets can be sent simultaneously
Devices can join or leave the network without affecting the overall network.
80
What are the disadvantages of a mesh topology?
The number of connections increase massively as more nodes are added
Rapidly becomes an impractical topology for wired network as so many cables would be needed.
Very expensive for a wired network due to cabling and switches needed
Needs complex co-ordination to be effective
81
What are the uses of the mesh network?
Music streaming devices around the home can use mesh topology to maximise range within the house as each device relays music to other devices within range.
In factories. Dozens of sensors on the assembly floor transmit data and relaying them into the factory network. If one sensor fails, the others just carry on.
The military have battlefield mesh networks in place to allow soldiers to communicate with one another, again because it is such a robust technology.
Surveying. A cluster of small drones can communicate with one another and act as a 'swarm'.
Rescue service. There are also experiments underway for a cluster of small robots to communicate using a mesh network for use in rescue situations such as collapsed buildings.
Mobile hot-spots. There are experiments underway to make a cars, taxis and buses mobile wi-fi hot-spots for citizens to use within a city.
82
What is ISP?
ISP stands for 'Internet Service Provider'.
An ISP is a company that provides access to the internet for business and individuals.
They usually charge a monthly fee for this service.
They will issue you with a user name and password and very often an email address.
For individuals, the ISP normally provides a modem through which you can log in and access the internet via one of the ISPs servers.
Examples of ISPs in the UK are (in no particular order):
Sky.
Virgin Media
Plus Net
BT Infinity
83
What is an URL?
URL stands for Uniform Resource Locator. It is pronounced "you-are-ell".
A URL is the unique web address for every webpage on the internet. For example 'www.teach-ict.com' is the unique url for the home page of this website.
84
What is an IP address?
This unique address for digital devices is called an IP address.
IP is short for Internet Protocol. An Internet Protocol is a set of rules that govern the activity on the internet and WWW.
An IP address is made up of a set of four numbers, each of which contains one to three digits, and is separated by a dot (.)
An example of an IP address might look something like this:
76.215.67.190
85
Why is an IP address needed?
There are literally billions of devices using the internet, computers, laptops, smart phones, tablets etc.
When you request some data from a webpage there has to be a way of getting that data delivered directly to your computer.
This is done by giving every single device connected to the internet its own unique address, a bit like you have a unique address for letters to be delivered to your home
86
How does the IP address made up as?
Each part of the IP address is presented as a denary number ranging from 0 to 255 - unlike MAC addresses which are presented in Hex format. (Extra fact: An IP address is actually stored as a binary number).
87
What are the two types of IP addresses?
IP addresses can be either static or dynamic.
As the name suggests, static IP addresses are permenant and never change.
Whereas dynamic IP addresses are temporary and are assigned to the device every time it accesses the internet. If you are using a dynamic IP address then your device will have a different IP address each time it joins a network to access the internet.
88
What is a DNS?
This is because there is the Domain Name System (DNS).
The task of the Domain Name System is to translate a web address into the correct IP address for the server or service that you have requested.
DNS servers have a database of IP addresses and they are constantly updated by other DNS servers.
89
What are websites hosted on and how would you acces it?
Websites are hosted on servers. A server is simply a computer and as we discussed earlier, every computer or device on the internet has its own unique IP address. Using the IP address of server where the web page is stored
90
How do you access websites from across the Internet?
- You type in the name of the website or web page that you wish to visit e.g. www.teach-ict.com.
- Your browser makes contact with a DNS server. The server contains a database that matches the domain name up with its registered IP address. (if it cannot find the address then it searches other DNS servers)
- The DNS sends this information back to your computer.
- Your computer 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 sends back the data which you requested
91
What are the advantages of DNS?
- You do not 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
92
What is a website?
A web site is made up of one or more web pages along with any images or other media such as video embedded within each web page.
All of these are saved as files, arranged just like any other set of related files - in folders.
93
How do the files of the website work?
The home page is the index.html file. The others are extra pages reached by some kind of navigation from the home page. Images are kept in their own folder to keep things tidy.
So a web site is a set of files and folders, with each web page file containing html markup code. This means that the web site can be stored on any computer or storage media. You can even store it in your own computer's normal file system, but that would make it difficult for others to access it.
94
What would you need to do for the website to work correctly?
For a web site to work correctly, it needs to be 'hosted' on a web server. Websites can be hosted either locally or externally
95
What is local hosting?
It is possible to host a website on your home PC. This is called 'local hosting'.
96
How would you do local hosting?
To do this you would need to set up your PC as a web server and allow others to connect to it and access the web files that you store.
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Why would some local host?
One reason is to save money, it costs less than using an external web host, and if the site is only for your own use or local network users, it is a good solution. There are a number of free, open source web server packages available that you can install.
You can also run a local database that is attached to the web server, so it is easy to set up your own personal blog if you want to. Packages like 'WordPress' is a free open source package that can do this.
If you are a web developer, then it is common to host a local copy of your site so you can test and update it properly before the site is uploaded to a public server.
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What are the issues with local hosting?
- Bandwidth: Your bandwidth from the local web server will be that of your broadband connection. This is unlikely to be enough for practical connections
- Always on: Your computer would need to be on all the time - not even sleep mode could be used.
- Technical knowledge: Although setting up a web server is straightforward, if things go wrong, it can take a lot of technical knowledge to find the problem.
- Firewall: It can be difficult to protect a web site from deliberate intrusion attempts and malware.
- Payments: If you are going to sell anything from your website then you would need to set up a payment gateway (not easy) and have very strong encryption and security in place.
- Dynamic IP: The IP address for your home internet connection is usually supplied by your Internet Service Provider (ISP). This is usually a dynamic IP address meaning that it changes every time the router connects to the ISP. This means there is no permanent IP address that can be used to connect to the server.
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What is external web hosting?
External hosting is where you pay a web hosting company to host your website on one of their servers.
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How are other organisations able to web host?
There are many companies who specialise in providing web hosting services, owning vast banks of servers (powerful computers).
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What will web hosting companies provide for a monthly charge?
As part of the monthly charge they will:
- provide hard disk space on their server to host your site
- ensure that your site remains running and available at all times
- provide the bandwidth required to allow users to access your site
- provide maintenance of the server
- regular backups of your site and if necessary provide a rollback
- provide security to protect your sites from malicious attack
- provide technical help
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What are the three types of external web hosting?
- Shared web hosting
- Dedicated server
- Virtual server
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What are the
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What is shared web hosting?
This is where many sites are hosted on the same web server.
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Why do people use shared web hosting?
The costs of running the server are shared between all of the users and so it is often the most economical way of having your website hosted.
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What are the downsides of shared web hosting?
The downsides are that all of the websites being hosted on the server have to share the same resources e.g. RAM, CPU time, bandwidth. So if one particular site on the server has a lot of web traffic or uses a lot of the CPU cycles then your site might experience poor performance.
Another downside is that you might have to accept advertising on your site. This sometimes happens with very low cost web hosting as the company offsets its lower charges with the advertising revenue.
Also they may only allow you to use the services supported by the web host. You may not be allowed to install specific modules or scripts that you want to run on your site
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What is ''dedicated server'' web hosting?
This is where the website is hosted on its own server, it does not share a server with any other sites.
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Who uses dedicated servers?
Dedicated servers are often used by companies who have a lot of website traffic. They may want to be sure that their website's performance is not affected by having to share with other sites.
Also, paying for a dedicated server means that you get faster, better quality support from the web hosts. Backups and server patching are carried out on a daily basis.
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What are the downsides of dedicated servers?
The downside is that this is an expensive option as you cannot share the costs of renting the server with other users.
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What is ''Virtual server'' web hosting?
This is a powerful server that runs specialist software allowing it to create many 'virtual servers' within itself. These are then rented out to customers to host their web site.
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Why do people use Virtual server web hosting?
This sharing of a single physical server to host many web sites means everyone shares the cost of it and so prices are kept low. It overcomes many of the issues of using the standard shared hosting service.
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What is 'the cloud' or 'cloud computing'?
The 'cloud' or 'cloud computing' refers to a range of software and services that run on the internet rather than on your PC.
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What are some cloud services?
Examples of cloud services are:
- online hosting of web page data
- online file and media storage (Dropbox, GoogleDrive)
- streaming services of films and other media (Netflix, Spotify, Amazon)
- online backups of your files (Carbonite)
- online applications e.g. Office 365, Adobe Creative Cloud, GoogleDocs
- Email services such as Yahoo Mail
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How do you access cloud services?
To access cloud services you need to use a web browser or a mobile app.
There is usually a charge for accessing services provided by these companies although some remain free to use, for example, GoogleDrive
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What are the advantages of cloud computing
The advantages of cloud computing are:
- you can access your data from any device with an internet connection
- documents and files can be worked on simultaneously by different people e.g. GoogleDocs
- you can store large files online and reduce the amount of storage space needed on your home device.
- you can access the latest versions of software - it won't ever become outdated
- online applications e.g. Office 365, Adobe Creative Cloud, GoogleDocs
- your work is automatically backed up, you don't have to remember to save it
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What are the disadvantages of cloud computing
The disadvantages of cloud computing are:
- if you don't have an internet connection you can't access any of the services
- if you forget your login details you can't access the services
- most of the services incur a cost, either a one-off payment or an ongoing monthly fee
- your files and personal data might not be stored in the UK and so won't be subject to the UK data laws
- there is a risk of online hackers being able to access your private data and files
