Computer Networks Flashcards
What is a network
A network is two of more devices connected together with the purpose of sharing resources
What is a local area network
A local area network (LAN) is a network which has a small geographical area
What is a wide area network
A wide area network (LAN) is a network which has a large geographical area
What are the factors that affect network performance
Number of Users
Bandwidth
Latency
Error Rate
Transmission Media
How does the number of users affect a network
Too many users can cause the network to slow down if there is not enough bandwidth for all of the data being sent and received
What is bandwidth
Bandwidth is the amount of data that can be sent and received at any given time
How does bandwidth affect a network
A smaller bandwidth means that less data can be sent and the network can slow down, potentially to the point of becoming unusable
What is latency
Latency is the delay between data being sent and received
How does latency affect a network
If there is a big delay between the two, more data will be on the network causing collisions
What is error rate
the measure of how many packets of data do not reach their destination
What is Transmission media
the type of cable used in wired connections
How does error rate affect a network
An increased error rate occurs in less reliable connections - a poor wireless signal would be a contributing factor to an increased error rate
How does transmission media affect a network
Wired connections offer a higher bandwidth than wireless connections
What is a Client-Server model
A client is a computer on the network, these connect to the server via a switch
What is a server
A server is a computer on a network which often has a single purpose
What are the advantages of client severs
-Managing backups of the network is easier as it is done from one central point
-Updating and installing new software can be done centrally
-Security of files can be managed easily
What are the disadvantages of a client server
-Servers can be expensive to purchase, setup and maintain
-A specialist network manager would be required as servers require specialist IT knowledge
-Servers can be a single point of failure, meaning all users would lose access to the network if the server fails
What is a Peer-to-Peer model
A peer is a computer on a network which is equal to all other computers
What are the advantages of a peer-peer server
-Very easy to set up and maintain
-Very cheap to set up because there is no expensive hardware to purchase
-No specialist knowledge or staff are required to run the network
What are the disadvantages of a peer-peer server
-Users will need to manage their own backups
-Users will need to manage their own software updates
-The network can be less secure
What is a router
The router is responsible for routing data packets between different networks
What is a wireless access point (WAP)
The Wireless Access Point (WAP) allows wireless devices to connect to a local area network (LAN)
What is a switch
A Switch allows multiple wired devices to connect to a local area network (LAN)
What is a network interface card (NIC)
The Network Interface Card (NIC) is required for a computer to connect to a network
What is the Internet
The Internet is a collection of networks spanning the whole world
What is a domain name system
a directory of domain names and is used to translate human-readable domain names to the numeric IP addresses that computers use
What are web servers
Web servers are dedicated servers that store web pages/websites and other resources
What are clients
Clients are end-users who make requests of web servers
What is hosting
Hosting is the storing of websites, files and other content on servers
What is the cloud
The cloud is a collection of servers which are used to store data, applications and files over the internet
What is a URL
Uniform Resource Locator: The web address typed into a web browser
What is a ISP
Internet Service Provider: the company that provides internet services to you
What is a network topology
A network topology is the physical structure of the network
What is a star topology
A star topology has a central switch which all other devices connect to
What is a mesh topology
A mesh topology allows all computers to be connected to all other computers
What is Ethernet
Ethernet is a wired networking standard to carry electrical signals between devices
What are the advantages of wired connections
Speed - Fast data transfer
Security - Better physical security
Range - High (up to 100m), less susceptible to interference
What are the disadvantages of wired connections
Portability - Can’t move easily, location is limited by physical cable
Cost - Need more cables to add a new device
Safety - Cables can be trip hazards, need routing along walls, under floors
What are advantages of wireless connections
Portability - Easy to move around, location is only limited by range
Cost - Less expensive to setup and add new devices
Compatibility - Most devices are manufactured with a built in Wi-Fi adapter
What are the disadvantages of wireless connections
Speed - Slower data transfer than Ethernet
Security - Less secure than Ethernet
Range - Relies on signal strength to the WAP, signals can be obstructed (up to 90m)
What is encryption
Encryption is a method of scrambling data before being transmitted across a network in order to protect the contents from unauthorised access
How is wireless data encrypted
-Wireless networks are identified by a ‘Service Set Identifier’ (SSID) which along with a password is used to create a ‘master key’
-When devices connect to the same wireless network using the SSID and password they are given a copy of the master key
-The master key is used to encrypt data into ‘cipher text’, before being transmitted
-The receiver uses the same master key to decrypt the cipher text back to ‘plain text’
How is wired data encrypted
Using a master key to encrypt data and the same key to decrypt data
What is an IP address
An IP (Internet Protocol) address is a unique identifier given to devices which communicate over the Internet (WAN)
What is a MAC address
A MAC (Media Access Control) address is a unique identifier given to devices which communicate over a local area network (LAN)
What is a standard
A computing standard is a set of guidelines that when used with different hardware and software allows them to work with each other and allow data exchange
What are the Examples of computer standards
HTML
Ethernet
USB
Wi-Fi
What is HTML
A standard for creating websites that allows them to be viewed on the World Wide Web (WWW) using web browser software
What is Wi-Fi
A standard that allows wireless devices to communicate on a local area network (LAN)
What is a protocol
A protocol is a set of rules that govern communication on a network
What is TCP
TCP is responsible for making sure communication between two routers is error free
What is IP
IP is responsible for making sure data is delivered to the right device on a wide area network (WAN)
What is HTTP
Hypertext Transfer Protocol (HTTP) allows communication between clients and servers for website viewing
What is HTTPS
HTTPS is used to protect sensitive information such as passwords, financial information and personal data
What is FTP
File Transfer Protocol (FTP) allows sending and receiving files between computers
What is SMTP
Simple Mail Transfer Protocol (SMTP) is a protocol that allows communication between an email sender and the email server, and between different email servers using the internet
What is POP
Post Office Protocol (POP) is a protocol for downloading emails to a device from an email server
What is IMAP
Internet Message Access Protocol (IMAP) is a protocol for downloading emails to a device from an email server
What is a layer
-A layer is a sub part of a more complex task
-Dividing network tasks into layers reduces the complexity and makes each layer more manageable
What are the 4 layers
-Application layer
-Transport layer
-Internet layer
-Network layer
What are the advantages of layers
-Layers are self-contained which makes managing, repairing and upgrading easier as each layer can be worked on independent of other layers
-Layers allow for focus on specific parts of a protocol without affecting other layers
