- Created by: KirstieTiny
- Created on: 08-05-19 18:40
LAN & WAN
LAN (Local Area Network)
- covers a small geographical area .
- located on a single site.
- all hardware for LAN owned by organisation that uses it.
- are wired or wireless.
- various devise can connet to a lan, e.g PCs, smart TV, printers.
- sharing files are easy.
- share same hardware.
- internet connection can be shared between all devices.
- install and update software on all computers at once.
- user account can be stored centally.
WAN (Wide Area Network)
- conects LANs that are in different geographical areas.
- more expencive than a LAN.
- may be connected using fiber or copper telephone lines, satellite links or radio links.
- the internet is an example.
Affecting Network Performance
- amount of data that can be transfered at a single time.
- shared between users of a network and so if too many users or heavy use may cause congestion can cause a slow network connection.
- you can limit the use of bandwidth for each person in the network
- are generally faster
- more reliable
- fiber optic cables can give much better performcance than copper cables
- wireless singnal depends on signal quality
NICs, Switches and Routers
Network Interface controller (NIC)
- internal piece of hardware that allows a device to connect to a network
- wired and wireless
- built into a motherboard
- connect devices on a LAN
- recieve and transmit data to the decixe on the network with correct MAC address
- transmitting data between networks
- connected to at least 2 different networks
- direct data packets to their destination
- connect LAN to the internet
Ethernet, coaxial and fibre-optic
- twisted pair cables containing 4 pairs of copper wires which are twisted together to reduce internal interface
- single copper wire surrounded by a plastic lay of insulation and metallic mesh, provding a shield from outside interference
- transmit data as light, high performance
- managed by a server
- devices connected to the server are clients
- files and software stored centrally
- the client sends requests to the server asking for data, the server processes the request and responds, which is known as the client-server relationship
- stores user profiles, passwords, and access information.
- easy to keep track of files
- easy to perform backups
- easy to install and update software
- easy to manage network security
- very reliable
- server dependence
- all devices are equal
- store files on individual devices
- may be used at home to share data/files
- easy to maintain
- no dependence on server
- no centralized management
- can create duplicate files, easy to lose track of what's stored where and which files are up to date
- less reliable and data may be lost if one fails
- slow down when other devices access them
- all devices are connected to the central switch or server that controls the network.
- a central switch allows many devices to access the server simultaneously.
- if the device fails or is disconnected then the rest of the network is unaffected.
- simple to add more devices
- better performance than other setups
- if there is a problem with switch or server then the whole network affected
- network devices are either directly or indirectly connected to every other one without need for a central switch or a server.
- work by sending data along the fastest route from one device to another
- no single point where it can fail
- if one device fails then data is sent along a different route so that it can reach its destination.
- wired mesh networks are more expensive but wireless ones are more practical.
- full mesh topology is where all devices are connected together but a partial mesh topology is where not all devices are connected.
- Set of rules
- How communication between 2 devices should start and end
- How the data should be organized and what devices should do if data goes missing
- Unique identifier
- Assigned to all network-enabled devices
- 48 or 64-bit binary number into hexadecimal
- E.g 10011000 10000001 01010101 11001101 11110010 00101111 =98-81-55-CD-F2-2F
- the Ethernet protocol on LANs allow the switches to read MAC Address and direct them to a device
- Used when sending data between TCP/IP networks
- Aren’t linked to hardware – can be assigned manually or automatically before the device can access network
- STATIC – permanent addresses used to connect printers on a LAN and for hosting websites on the internet
- DYNAMIC – assigned every time it logs onto a network so could get a different one each time you connect.
- It may change if you take a laptop to a new country and connect to a network over there.It may change if you take a laptop to a new country and connect to a network over there.
· Broken into equal packet sizes
· Given a header containing;
o IP its going to
o IP its come from
o Number of packets in sequence
o Error checking data
· Sent across internet separately following different routes
· Reassembled once it has reached the destination/recipient
· Any packets not received will be resent
Types of protocols
· HTTP (Hyper Text Transfer Protocol) – access to websites and communication with web server
· HTTPS (Hyper Text Transfer Protocol Secure) – a secure version of HTTP, encrypts all information it sends and receives.
· FTP (File Transfer Protocol) – edit and move files on a network
· POP3 (Post Office Protocol – version 3) – retrieve emails from a server, server holds until you download it at which point it is deleted from the server
· IMAP (Internet Message Access Protocol) – retrieve email from server, server hold until you delete it and you only download a copy
· SMTP (Simple Mail Transfer Protocol) – Used to send emails, and used to transfer emails between servers
· A layer is a group of protocols with similar functions
· They are self contained – they do not need to know what is happening in other layers in order to function
· Each layer serves the layer above it.
Layer 4 – Application layer
Layer 3 – Transport layer
Layer 2 – Network layer
Layer 1 – Link layer
· Communication is in manageable pieces
· Self contained – edit one and not affect the others
· Makes compatible universal hardware
The internet is a worldwide web
· The internet is a network of networks
o A WAN that connects devices and networks all over the world, it is based around the protocol TCP/IP.
· The World Wide Web (WWW) is a collect on websites that are hosted on web servers using the HTTP protocol.
· URLs are addressed used to access web servers and resources on them.
· A Domain Name Server (DNS) translate a website’s domain name into its IP address. The internet has a network of DNSs meaning you don’t have to remember the IP Address to access a website so you can use a domain name instead.
· Hosting is when a business uses its servers to store files of another organisation.
- Users can access files from any connected device.
- Easy to increase storage availability
- No expensive hardware
- No IT staff needed to manage storage
- Cloud host provides security and backups for you
- Cloud software will be updated automatically
- Need connection to internet to access files
- Dependant on host for security and backups
- Vulnerable to hackers
- Unclear who has ownership of data
· A network that is entirely software-based.
o Created by partitioning off some of a physical network's bandwidth to form a separate network.
· Several virtual networks exist on the same physical network. These networks all share the same hardware making virtual networks more efficient.
· Has own security including its own firewall so can only be access with certain software or login details.
· A VPN is a Virtual Privet Network that can be used to send data securely over a large network, like a WAN or the Internet.
· A virtual LAN allows you to split up a network into several separate networks using the same hardware.
· Passive attack – where someone monitors the data traveling on a network and intercepts any sensitive data that they find. Network monitoring software is used to see what each type of data is being transferred.
· Active attack – someone attacks a network with malware or other planned attacks. These are easier to detect and can be stopped with a firewall.
· Insider attack – someone within a network uses their access to steal information.
· Bruit force attack – gaining information by cracking passwords using trial and error. Normally they are automated software that produces hundreds of likely password combinations. By locking accounts after a certain number of attempts and using strong passwords will stop or so down the process.
· Dos attack – stopping a user from accessing a part of the network or website, by flooding with useless traffic making network really slow or making it crash.
People are the weak points of a system
· People can give personal information in many ways:
o Social engineering – influencing people and gaining personal information
o Telephone – someone pretends to be a person from well known business requesting personal information.
o Phishing – getting emails suggesting something bad will happen if you don’t click on the link.
· Data base query language
· One of the main coding languages used to access information in databases
· SQL typed into a websites input box which then reveals sensitive data/information
Good network policy
· Will have:
o Regular tests to find and fix security weaknesses and investigate any problems
o Use passwords to prevent unauthorised access
o User access levels to limit number of people who can access sensitive information
o Install anti-malware and firewall software to prevent and destroy software attacks.
o Encrypt sensitive data
· Also known as pentesting is when organisations employ specialists to simulate potential attacks on their network
· Used to identify possible weaknesses in a networks security
· The results are then resulted back
· Investigations undertaken to find out the cause of attacks on networks
o Need to have system of capturing data packets as they enter a network
· After a network is attacked these packets can be analysed to discover how a network was attacked and decide how to prevent future attacks.
· Prevent unauthorised users accessing a network
· Passwords need to be strong in order to protect peoples sensitive data – should be a long consist of a range of letters and numbers, in both capital and lowercase
User Access levels
· Controls which group of people can access which information on a network
· Helps to limit the number of people with access to important information
o prevent insider attacks
· Find and stop malware from damaging a network
· Lots of different types like anti-virus softer, which isolate and destroy and infected data.
· Companies use firewalls to block unauthorised
· Data transferred into code, where someone with the encryption key and access
· Text called cipher text is encrypted and plain text is the opposite
· Essential for sending data over a network securely.