9. Fundamentals of Communications and Networking Flashcards
What are the 2 types of networks?
Local area network (LAN) and wide area network (WAN)
What are the 2 types of network topologies?
Bus and star
Describe the set up of a bus topology.
Nodes are connected in a daisy chain along a single central communications channel.
Describe the set up of a star network.
A central node of hub provides a common connection point.
What are the features of a bus network?
- Requires CSMA/CD technology to prevent crashes- Data sent in one direction at a time- Terminator connected to the end of the backbone to prevent signals bouncing back
What is the difference between a hub and a switch?
The hub broadcasts the messages to everyone on the LAN, whereas the switch only broadcasts to the intended recipient
What is a server?
A powerful computer which provides services or resources requested by clients. Like the waiter.
What is a client?
Computer which does the requesting.
What are the 2 types of networks?
Client-server, and P2P
What are the features of a client server network?
- Central server is used to manage security- Some files are held on the central server to save retrieval time- Some of the processing is done by the server- Client requests- Requires specialist to administer network
What are the features of a P2P network?
- Suitable for small computers- No central servers- All computers can easily see each others files- No server required for comms- Data is futile
What is P2P commonly used for?
Illegal data streaming (torrent)/file sharing sites
What is the cloud?
A remote server run by organisations such as Dropbox or Microsoft
What is a common serial data cable?
USB
What is a common parallel data cable?
Ribbons used to connect internal components.
What are the features of serial transmission?
Bits are sent one by one in a single direction along a single data line.
What are the features of parallel transmission?
- Several bits are sent at once along separate lines- Only works well up to 2m- Skew and crosstalk are disadvantages
What is skew?
When the bits of data are sent along parallel transmission cables and arrive at different times due to faults in wires - data is received corrupted
What is crosstalk?
EM interference corrupting the data during transmission (more common in parallel to the amount of wires)
What is the difference between synchronous and asynchronous transmission?
In sync, all data is transmitted in time with the clock. In async, bytes of data is sent as soon as there is available space.
What is the issue with async?
Although cheaper, the transmission is slower.
What is the pro of async?
Includes a parity bit, which provides error detection.
What is latency?
The delay between the first byte being sent and received.
What are some common elements of protocol?
- Rate of transmission- Data format- Error checking
How do you calculate the bit rate?
Bit rate = baud rate x number of bits per signal
What are the key elements of networked devices?
WAP (+ router + modem), NIC, MAC, SSID
What is a WAP?
Wireless network access point.
What is a NIC?
Network interface card.
What is the SSID?
Name of the network (e.g. BT-PWTSK)
How are collision prevented?
With the use of CSMA/CD
What feature does CSMA include?
RTS/CTS (request to send, clear to send)
How can you secure networks?
Using WPA, WPA2 or MAC address whitelists
Describe a client server network.
Where networked computers (clients) are connected to one of more powerful computers (servers) that handle service requests and has resources.
Describe a logical bus topology.
A network arrangement where every host computer is connected to a single main data cable
Describe a peer-to-peer network.
A network where computers are connected to each other with equal status and share resources and workloads without any central server.
Describe a physical star topology.
A network arrangement where every host computer has a dedicated connection to a central hub or switch.
What are firewalls?
A security checkpoint application that monitors incoming and outgoing network traffic
What are internet registries?
Organisations responsible for distributing domain names and IP addresses.
What is a digital certificate?
An electronic document proving ownership of a public key and hence authorising your identity.
What is a digital signature?
A mathematical scheme for producing a unique signature that verifies the authenticity of encrypted digital messages.
What is a gateway?
A device that allows data to flow form one network to another.
What is a MAC address?
A hardware ID number assigned to the NIC to uniquely identify a device on a network for communication purposes.
What is a packet?
A block of data.
What is a router?
A device used to direct packets being transmitted between networks.
What is an IP address?
A numerical address assigned to any device communicating via the internet.
What is asymmetric encryption?
An encryption technique where a public key available to everyone is used to encrypt the data, but decrypted with a private key known only to the recipient.
What is bandwidth?
The range of frequencies at which data can be transmitted through a channel, measured in Hz.
What is baud rate?
The number of signal changed per second.
What is bit rate?
The number of bits transmitted per second.
What is CSMA/CD?
A wireless protocol where computers avoid collisions by transmitting only once the channel is idle.
What is packet switching?
A method for sending data over a network by breaking data into several data packets which are sent independently and then reassembled once they arrive.
What is protocol?
A common set of rules followed during data transmission.
What is RTS/CTS?
Request to send/clear to send - A protocol to prevent collision during wireless transmission, involving an additional RTS and CTS signal being sent for idle confirmation.
What is symmetric encryption?
A encryption technique where the same key is used to encrypt and decrypt. A copy of the key must be sent between both parties.
What is the DNS?
Domain name server - A naming system for computer systems connected to the internet. Contains the IP addresses of all domain names on the internet.
What is the internet?
A global network of computer systems using TCP/IP
What is Wi-Fi?
A wireless local area network that is based on international standards.
What is WPA/WPA2?
A security certification program that secures wireless networks by encrypting transmitted data.
What is a trojan?
A malware that hides within another file and misleads the user of its true intent.
What is a virus?
A program that attaches itself to another computer file to infect a computer system by replicating itself and inserting its code into other files.
What is a worm?
A standalone virus capable of spreading and infecting a computer without being attached to a file.
What is TCP/IP stack?
A suit of networking protocols that allow networked computers to communicate, consisting of four layers.
Email server
A computer system on a network designated to handle emails being sent and received by other computers on the network.
File transfer protocol (FTP)?
Used for downloading or uploading files from a computer system.
Hyper Text Transfer Protocol (HTTP)?
Used to fetch, render and transmit webpages.
Hyper Text Transfer Protocol Secure (HTTPS)?
An encrypted version of HTTP
Post Office Protocol Version 3 (POP3)?
An application layer standard protocol used to receive emails from a server.
Secure Shell (SSH)?
A cryptographic network protocol for secure and remote access to computers.
Simple Mail Transfer Protocol (SMTP)?
Internet standard communication protocol for sending emails.
What is a web browser?
An application software used to view webpages a computer system has requested from a web server.
What is a web server?
A computer system on a network designated to handle web requests through HTTP(S).
What does an IP address consist of?
Host and network identifiers.
What is a subnet?
A smaller network that forms a subset of a whole network.
What is a non-routable IP address?
A private IP address used for devices on a private network hidden behind a router or a firewall.
What is a routable IP address?
A public IP address that is register under the DNS.
What is Dynamic Host Configuration Protocol (DHCP)?
A protocol for allocating unique dynamic IP addresses for computers on local networks when the local network attempts to connect to the internet.
What is Network Address Translation (NAT)?
Mapping a private IP address to a public IP address by modifying address information in the packet header when it is being sent through the router.
What is port forwarding?
Routing data through additional port to allow a server in a non-routable network to provide services to the internet.
What is a client-server model?
A model where the client send requests to the server and the server responds with a response message.
What is a CRUD application?
A web application with create, retrieve, update and delete functionality.
What is Extension Markup Language (XML)?
A markup language for econding documents to be sent over a network in a human and machine readable format.
What is JavaScript Object Notation (JSON)?
A human readable file format used for transmitting information in attribute-value pairs and arrays.
What is REST?
A representational state transfer method used to map a networks functionality to database operations.
What is Web Socket Protocol?
A protocol defining an API, establishing a full-duplex ‘socket’ connection between a web browser and a server over TCP. This create a persistent connection between client and server.
