Fundamentals of Communication and Networking Flashcards
Bandwidth
The range of frequencies that a communication medium is capable of transmitting
Latency
The difference in time of an action being initiated and its effect being noticed
Protocol
A set of rules for communication between devices
Serial Data Transmission
Data is transmitted through a communication line one bit at a time
Parallel Data Transmission
Uses multiple parallel communication lines to send multiple bits simultaneously
Skew
When bits that are sent together may not be received together
Crosstalk
When signals leak from one line into another which causes data corruption
Synchronous Transmission
When data is sent between devices who have their clock speed’s synchronised so data is received in the same order they were sent
Asynchronous Transmission
Uses start and stop bits on either side of the transmission in order time the clock signals of the communicating devices
Topology
The structure of a network
Star Topology
Network structure where there is a central switch where all client are directly connected to
Bus Topology
Network structure where there is a single cable (backbone) which every client is connected to
Client-server Networking
Type of network where clients are connected to one or more central servers which allow the clients to access all resources
Peer-to-peer Networking
Type of network where all clients together act as a server to perform and share resources but certain ones are lost when clients are switched off
Service Set Identifier (SSID)
Name that identifies a wireless network
Media Access Control (MAC)
Unique addresses are assigned to every wireless device by the manufacturer
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
Protocol used in wireless networks to avoid data collisions when multiple devices are communicating by listening to communication channel and sending data if it’s idle, if not, it waits a random period of time
Request to Send/Clear to Send (RTS/CTS)
This is added on to CSMA/CA to avoid hidden nodes by checking whether the network is idle
The Internet
Network of interconnected computer networks
Internet Service Provider (ISP)
Company which provides their customers access to the internet
Packet
Container in which data is sent over networks
Packet Switching
Data transmission where data is broken into packets which are sent across the internet via optimum routes and are then reassembled at the destination
Primary Components of a Packet
Sender’s address
Recipient’s address
Time To Live (TTL) - Number of hops a packet can do before being dropped
Packet contents
Sequence number
Router
Network device that forwards data packets between computer networks
Gateway
A computer which that sits between different networks or applications
Uniform Resource Locator (URL)
An address which is assigned to files on the internet
Parts of the URL (7)
Protocol
Subdomain (www)
Domain - Name of the organisation
Directory of file being requested (e.g. /news)
Subdirector of file being requested (e.g. /technology)
Name of file being requested (e.g. /index)
File’s extention (e.g. html)
Domain Name
Identifies an organisation or individual on the internet
Domain Name System (DNS)
Turns domain names into IP addresses which allows browsers to get to the websites
Firewall
Sits between the internet and the device and regulates the packets that pass through, can perform packet filtering and stateful inspection
Packet Filtering
Can accept and block certain packets based on source IP address or protocol they are using
Stateful Inspection
Examines the contents of the packets before allowing it through the firewall
Proxy Server
Sits between a public and private network, regulating all the packets that pass through
Symmetric Encryption
Both the sender and receiver have the same private key to encrypt and decrypt data send between the two parties
Asymmetric Encryption
Four keys are used in encryption/decryption as there is a public key in which the data is encrypted but only the private key can decrypt it and vice versa
Digital Signatures
These are used for asymmetric encryption to verify the sender of the data and whether the data has been tampered with
Digital Certificate
Verifies the ownership of a key pair (public and private key) during asymmetric encryption
Worms
Type of malicious software which can automatically self-replicate and infect other devices on the network
Trojans
Type of malicious software that is disguised as a safe/legit file but contains malware when opened or downloaded
Viruses
Type of malicious software that attaches itself to programs or files so it can replicate and spread through the computer
TCP/IP model
Defines how devices should transmit data between then and enables communication over a large distance
Application Layer
Layer of the TCP/IP model which determines which protocol to use for communication and provides the interfaces needed by the user
Transport Layer
Layer of the TCP/IP model which splits up the data into packets, containing their sequence number and what they consist of and ensures error-free, end-to-end delivery of data
Network Layer
Layer of the TCP/IP model which handles the routing and sender of the packets across networks
Link Layer
Layer of the TCP/IP model which facilitates the transmission of the packets across a network (physical layer) to reach the destination MAC address
Structure of IPv4 address
Network identifier - What network it is on (3 bytes)
Host identifier - What PC in that network (1 byte)
Subnet Mask
Sequence of binary digits, 1s are repeated until the network identifier has been shown. Mask is ANDed with IP address
IPv4 address
32 bits
IPv6
128 bits
Routable IP address
Uniquely assigned to devices which are directly connected to public/global internet
Who are Routable IP addresses assigned by?
Global organisations like IANA
Non-Routable IP Addresses
(PRIVATE) - Assigned to devices on a private network
Network Address Translation (NAT)
Converts IP addresses as they get transferred between public and private address spaces (Router)
Port Number for HTTP
80 and 8080
Port Number for FTP
20
Port Number for POP3
110
Port
Allows the TCP/IP protocol to decide which application should deal with the packet when it arrives
Dynamic Host Configuration Protocol (DHCP)
A DHCP server is a device which is responsible for automatically assigning a dynamic IP address from a pool of available addresses to computers which operate on a private or public network
