2.1 Networks including the internet Flashcards
What is a LAN (local area network)?
A LAN (Local Area Network) is a computer network that connects computers within a local limited area, such as a home, a school or an office building.
A LAN was traditionally connected via cables, meaning all devices had to be connected to a network port or another computer within the network system.
As technology developed, LAN networks allowed for local wifi connections, allowing devices to connect wirelessly to the local network connection. This allowed more flexibility on the number and type of devices that could connect to the network. (WLAN)
Show understanding of the characteristics of a WAN (wide area network)
A WAN network (Wide Area Network) is a telecommunications network that extends the network device over a large geographical area.
The most common WAN network is the internet, as you are able to access it via a cabled or wireless connection anywhere in the world. Mobile broadband connections such as 4G and 5G allow mobile devices to access the internet from anywhere with a strong enough wireless signal, usually within range of an area’s telecommunications satellite.
WAN networks are also used within companies and organisations, allowing communications and file sharing across multiple campuses. InterHigh is a good example of a WAN as students and staff may access content anywhere in the world.
WAN networks typically consist of a number of LANS connected connected via public communications networks (telephone lines or satellites).
Because a WAN consists of LANs joined together, it may be private, requiring user IDs and passwords to access it. (e.g. InterHigh)
The internet is not a private network and consists of a number of decentralised networks and computers which have a common point of access, so that anyone with access to the internet can access devices on these networks.
What benefits are there to networking devices?
• Devices, such as printers, can be shared (reducing costs of the number of devices needed)
• Licenses to run software on networks are often far cheaper than buying licenses for an
equivalent number of standalone computers (e.g. Office 365)
• Users can share files and data
• Access to reliable data comes from a central source, such as a file server.
• Data and files can be backed up centrally at the end of each day.
• Users can communicate using email and instant messaging
• A network manager can oversee the network and offer support to user or apply/restrict access to external networks, such as the internet
What are the drawbacks of network devices?
- Cabling and server connections can be expensive to initially set up.
- Managing large networks can be a complex task
- A breakdown of devices, such as file servers, can affect the whole network
- Malware and hacking can affect entire networks (particularly if a LAN is part of a much larger WAN), although firewalls do offer some protection in this respect.
Networked computers form an infrastructure which enables internal and external communications to take place. What is the network infrastructure?
Hardware:
• LAN cards, Routers, Switches, Wireless Routers, Cables
Software:
• Operation & management of a network, Operation of firewalls, Security
applications/utilities
Services:
• DSL (Digital Subscriber Line), Satellite communication channels, Wireless
protocols, IP Addressing
What are wireless access points (WAP)?
When connecting to a wireless network, devices known as Wireless Access Points (WAP), are connected into the wired network at fixed locations.
The WAP received and transmits data between the WLAN and the wired network structure.
As their connection is limited to within a short distance, many establishments require several WAPs to maintain a consistent wireless connection.
Explain the client-server model
The client-server model uses separate dedicated servers and specific client workstations; client computers will be connected to the server computer(s).
Users are able to access most of the files, which are stored on dedicated servers. The server dictates which users are able to access which files, and can install software onto clients’ computers.
The model uses central security database with control access to shared
resources, and can be implemented on a large scale as they are easily scalable. Further, if someone deletes a shared resources from the server, a nightly back-up would restore the deleted resource
The issues caused by bottle necking can become expensive if it causes disruption within a computer system. How can this be reduced?
Some methods for reducing this include:
• Segmenting the LAN into a series of virtual networks (VLANs) to distribute the
data load more evenly
• Cabling the network so the data travels between the appropriate switches
Explain the peer-to-peer server model
A peer-to-peer model does not have a central server. Each of the nodes on the
network can share its files/data and communicate with all the other nodes, and each node will have its own data. Because there is no central storage, and no requirement to authenticate users. The services available are listed on a nominated ‘look-up’ computer.
The provision of services to all other network users; the services available are listed on a nominated ‘look-up’ computer.
-When a node requests a service, the ‘look-up’ computer is contacted to find out which node can provide the required service.
A peer-to-peer model is used in workplace applications where no more than 10 nodes are required (e.g. a small business) where it is relatively easy for users to be in contact with each other on a regular basis. More than 10 nodes leads to performance and management issues.
Peer-to-peer offers little data security since there is no central security system. This means it is impossible to know who is authorised to share certain data. Users can create their own network node share point which is the only real security aspect since this gives them some kind of control, although there are no real authentication procedures.
Give two differences between the client-server model and the peer-to-peer model
- Peers to be both suppliers and consumers (unlike the client-server model where consumers and resources are kept separate from each other)
- Peers can participate as equals on the network (again this is different to the client-server model where a web server and client have different responsibilities)
The client-server model offers thin clients and thick clients. What are thin clients?
A thin client is heavily dependent on having access to a server to allow constant access to files and to allow applications to run uninterrupted.
A thin client can either be a device or software which needs to be connected to a powerful computer or server to allow processing to take place.
The thin client will not work unless it is connected at all times to the computer or server. A software example would be a web browser which has very limited functions unless it is connected to a server.
Pros and cons of a thin client
Pros
• Less expensive to expand (low-powered and cheap devices can be used)
• All devices are linked to a server (data updates and new software installation is done centrally)
• Server can offer protection against hacking and malware
Cons
• High reliance on the server; if the server goes down or there is a break in the communication link then the devices cannot work
What is a thick client?
A thick client can either be a device or software that can work offline or online; it is still able to do some processing whether it is connected to a server or not.
A hardware example is a normal PC/laptop/tablet since it would have its own storage, RAM and operating system which means it is capable of operating effectively online or offline.
An example of software is a computer game which can run independently on a user’s computer, but can also connect to an online server to allow gamers to play and communicate with each other.
Pros and cons of a thick client
Pros
• More robust (devices can carry out processing even when they are not connected to the server)
• Clients have more control (they can store their own programs and data/files)
Cons
• Less secure (relies on clients to keep their own data secure)
• Each client needs to update data and software individually
• Data integrity issues, since many clients access the same data which can lead to inconsistencies
What is a bus network topology?
A bus network topology uses a single central cable to connect all devices. It is easy to expand and requires little cabling, but data can only travel in one direction; so if data is being sent between devices, then other devices cannot transmit.
Bus networks are typically peer-to-peer and terminators are needed at each end to prevent signal reflection (bounce).
Each node looks at each packet and determines whether or not the address of the recipient in the packet matches the node address. If it is a match, the node accepts the packet; if not, the packet is ignored.
What pros and cons are there of a bus topology network?
Disadvantages to bus networks include:
• If the main cable fails, the whole network goes down
• The performance of the network deteriorates under heavy loading
• The network is not secure since each packet passes through every node
Advantages of bus networks include:
• Even if one node fails, the remainder of the network continues to function
• It is easy to increase the size of the network by adding additional nodes
What is a star topology?
A star network uses a central hub/switch, which each node is connected to.
Data going from host to host is directed through the central hub/switch.
Each computer/device has its own dedicated connection to the central node
(hub/switch) – any type of network cable can be used for the connections.
A star network typically uses a client-server model.
What advantages and disadvantages are there to a star topology network?
Disadvantages of a star network include:
• The initial installation costs are high
• If the central switch/hub fails, then the whole network goes down
Advantages of star networks include:
• Data collisions are greatly reduced due to the topology
• It is a more secure network since security methods can be applied to the central node and packets only travel to nodes with the correct address
• It is easy to improve by simply installing an upgraded central node
• If one of the connections is broken it only affects one of the nodes
Explain how packets are handled differently in a star topology depending if the central node is a switch or a hub.
If the central node is a hub, all the packets will be sent to every device/node on the star network – if the address in the packet matches that of the node it will be accepted; if not, it will be ignored (similar to a bus network)
If the central node is a switch, packets will only be sent to the nodes where the
packet address matches the recipient address. This is clearly more secure, since only the intended nodes will receive the packets.
What is a mesh topology?
There are two types of mesh network topologies: Routing and Flooding
Routing works by giving the node routing logic (making them act like a router) so that data is directed to its destination by the shortest route and can be re-routed if one of the nodes in the route has failed.
Flooding simply sends the data via all the nodes and uses no routing logic, which can lead to unnecessary loading on the network.
What advantages and disadvantages are there of mesh topology networks?
Disadvantages of mesh networks include:
• A large amount of cabling is needed, which is expensive and time consuming
• Set-up time and maintenance is difficult and complex
Advantages of mesh networks include:
• It is easy to identify where the faults on the network have occurred
• Any broken links in the network do not affect the other nodes
• Good privacy and security, since packets travel along dedicated routes
• The network is relatively easy to expand
What is a hybrid topology?
A hybrid network is a mixture of two or more different topologies (bus & star, bus & mesh, etc.)
The main advantages and disadvantages depend on which types of network are used to make up the hybrid network, but an additional disadvantage is that they can be very complex to install, configure and maintain.
What advantages and disadvantages are there to a hybrid topology network?
Advantages of a hybrid network include:
• They can handle a large volume of traffic
• It is easy to identify where the network fault has occurred
• They are very well suited to the creation of larger networks
Disadvantages of a hybrid network include:
• very complex to install, configure and maintain.
Other main advantages and disadvantages depend on which topology types of are used to make up the hybrid network
What is cloud computing?
Cloud Storage is a method of data storage where data is stored, managed, and processed on remote servers on the internet, rather than a local server or a personal computer – the physical infrastructure covers hundreds of servers in many locations.
The same data will be copied and stored in more than one location in case of server maintenance and repairs, allowing clients to access data at any time.
This process is known as data redundancy and will be carried out by a cloud hosting company to protect the data of their clients.
What is private cloud storage?
Private Cloud storage allows a company to implement security measures across the company whilst keeping all of their files on a cloud server.
The storage on a private cloud will be provided by a dedicated environment behind a company firewall. The customer/client and cloud storage provider will be integrated and operate as a single entity.
A company that would use a private cloud is IBM. They will have their own dedicated service that will require logins for staff and clients. They are not hosted by Google or Microsoft and have their own dedicated infrastructure.
