Networks Flashcards
Define serial transmission
Data is sent one bit at a time down a single wire
Define parallel transmission
Data is sent multiple bits at a time down several wires
Define bandwidth
A measure of the capacity of the channel down which the data is being sent. It’s measured in hertz (Hz)
State what is meant by bit rate
The rate at which data is actually being transmitted. Measured in bits per second
What is latency?
The time delay that occurs when transmitting data between devices
State what is meant by asynchronous data transmission
Data being transmitted between two devices that do not share a common clock signal
State what is meant by synchronous data transmission
Data is transmitted where the pulse of the clock of the sending device and receiving device are in time with each other. The devices may share a common clock.
What are protocols? Give some examples of protocols used in networks
Protocols are a set of rule.
TCP/IP are a set of protocols for all TCP/IP network transmissions.
HTTP (HyperText Transfer Protocol) are a set of rules to define the identification, request and transfer of multimedia content over the internet.
FTP is a set of rule for handling file uploads and downloads.
What is a network?
Devices that are connected together to share data and resources
state what a network interface card (NIC) is
A card that enables devices to connect to a network
What is meant by LAN and WAN?
LAN (Local Area Network) is a network over a small geographical area - usually one site and typically used by one organisation.
WAN (Wide Area Network) A network spread over a large geographical area.
Define what a network topology is and give some examples
A network topology is usually in terms of conceptual layout of a network rather than the physical one.
Two example of network typologies are bus and star.
What is the bus network typologies and state some advantages and disadvantages
Bus - A network layout that uses one main data cable as the backbone to transmit data. Advantages : Cheaper and easier to install than a star topology and easy to add new devices to the network.
Disadvantages: less secure than a star topology, Slow transmission times one larger bus networks, if the main cable fails then all networks are affected, Less reliable than a star topology due to the reliance on one cable, Difficult to fault find.
What is the star network typologies and state some advantages and disadvantages
Star When each device on the network is connected to a central computer or switch via it’s own cable. disadvantages : more expensive and harder to install than a bus topology and harder to add new devices to the network, if a cable fails that client may not be able to receive data.
Advantages: more secure than a bus topology, little slow down on large networks, If one cable fails then only one client is affected, fault finding is easier than on a bus network.
Define what is meant by client-server
A network methodology where one computer has the main processing power and storage and the other devices on the network act as client and request services from the server.
Define what is meant by a Peer-to-peer network
A network methodology where all devices in a network share resources between then rather than having a server.
Define what a WWAN is
A WAN that doesn’t use cables but send data wirelessly
What is a MAC address?
Media Access Control address is a unique code that identifies a particular device on a network
What is WIFI?
A standard method for connecting deices wirelessly to a network and to the network and to the internet
Define what a WLAN is
A LAN that doesn’t use cables but send data wirelessly
What is SSID?
Service Set Identifier - A unique 32-character code that identifies a device on a wireless network. Used to make sure the devices on a wireless network are connecting to the right WLAN.
What is the RTS/CTS protocol?
Request to send /clear to send - A protocol to ensure data doesn’t collide when being transmitted on a wireless network. The device wishing to send data sends the RTS signal and waits for the CTS signal, if it receives the CTS signal it knows the receiving end is idle. If no CTS signal is received it the sender waits a random amount of time and then re-sends the RTS signal.
How do you improve security on a wireless network?
- Change the SSID from the default and hide it from transmission.
- Ensure all devices are WPA/WPA2 compliant.
- Use strong encryption (WPA/WPA2).
- Create a white list of MAC addresses from the devices you want to access the network.
What is WPA/WPA2?
WIFI Protected Access (WPA/WPA2) is a protocol for encrypting data and ensuring security on WIFI networks
What is the internet?
A global network of networks. It started life as ARPANET in the late 1960’s. The internet as we know it was created in the mid 1980’s when a British scientist created the World Wide Web (WWW).
Define URL
Uniform Resource Locator (URL) - A method for identifying the location of resources (e.g. websites) on the internet.
When HTTP is included with a URL what does it indicate?
When HTTP is used as part of a web address it indicates that the file can be accessed using a browser. Most URLs start with HTTP, although it’s not necessary to type it into the address line.
Define domain name
Domain name is the recognizable name of a domain on the internet.
What is an IP address?
Internet Protocol address (IP address) is a unique dotted quad number that identifies devices on a network. These numbers make little sense to people so instead we use domain names to represent the IP address.
What is used to go from a domain name to an IP address?
To convert a domain name to an IP address, so the data transmitting protocols can be used, we use a domain name server. This is a server that contains domain names and associated IP address.
What is a non-routable/private IP address?
This is an IP address used on a private network (e.g. a home or school). Despite the IP address being needed in order to route around a network this address doesn’t need to be made public as the device isn’t directly connected to the internet as it can be hidden behind a firewall or router.
Define port
A port is used to identify a particular process or application on a network. Such as POP3 which is a protocol used for receiving emails. Port addresses are often used for processes that are common in networking task and many have been assigned port numbers that are in wide spread use. There are around 250 common ports.
What is SSH?
Secure Shell (SSH) Protocol is a protocol for remote access to computers.
How do you match up private IP addresses with public ones?
A process called Network Address Translation (NAT). Using this has 2 main advantages;
1) A unique IP address isn’t needed for every device on a network, only the router or server that is physical needs one
2) There is an increased level of security as the private IP address isn’t being broadcast over the internet
What name is given to the system of connected DNS that provides the IP addresses of every website on the internet?
Domain name server (DNS) system
How does NAT work?
The router maps all the private IP addresses to a port number and the corresponding public IP address. The workstation trying to access the internet will send a packet containing the data it wants to send, its own internal IP and the port number that it generates. The router then logs the internal IP address and the port number and replaces them with its external IP address. When data is sent back to the router it looks at the port address it was sent back to and looks it up in the table that it saves the internal IP addresses and corresponding port numbers to and sends the data the the relevant internal IP address. Id the table doesn’t contain a matching port number the packet is dropped.
