Networks(Not done (do e)) Flashcards
What is a WAN
Wide area Network
WANs are typically spread across a large geographical area aNd relies on third party carriers or communications
What is the internet?
Network of interconnected Networks set up to allow computers to communicate with each other globally
What is a LAN?
Two or more computers connected togather within a small geographic area
What are Protocols?
Defines a set of rules required for data communication between devices
to govern transmission of data
What is Circuit switching?
Circuit switching involves creating a communication between two endpoints for the duration of the transfer of data
No other data can use any part of this circuit until the transmission is complete
data packets used
What are data packets?
When sending across a network,data is broken into equal size chunks(units) called data packets and assembled again at the receiving end
How do data packets help
they improve efficiency and reliability
What is packet switching?
Packets are often sent across a network on which other similar communications are happening simultaneously
(network often shared)
What is routing?
Routers transfer data packets from one network to another
What is a ‘Hop’ in terms of routing?
Each transfer from a router is known as a hop
Routing process
Each router stores data about the available routes to the destination
looks up the destination IP ADDRESS (in its routing table)and finds best router to forward the packet to
Routers continue to forward the packet until destination node is reached
Why are packets deliberately kept small?
To ensure that the packets do not take excess time to transfer preventing other packets from moving
What is required when data is transferred from one network to another but with different protocols?
A gateway
What is a MAC address?
Uniquely identifies a physical device with a network interface card(NIC)
It is 48 bits long and written in 12 digit hex
What is client-server?
is a model where one entity (the client) requests services from another (the server)
What is peer-to-peer?
have equal status
each computer on the network acts as both client and server there is no centralized control
what is an IP address?
An IP address is a unique address that is assigned to a network device
Differences between circuit and packet switching
CS establishes a route for the duration of the message/PS has no established route
CS sends packets all on same route/PS means packets being sent on individual routes
CS packets remain in correct order (but must be reassembled)/PS packets arrive out of order (and must be reordered)
What does an IP address indicate?
An IP address indicates where a packet of data is to be sent or has been sent from
What is a URL?
Uniform Resource locator is the full address of an internet resource.It specifics the location of a resource on the internet
What is a Domain name?
A domain name identifies the area or domain that an internet resource resides in
One feature of a LAN
LANs can transmit data very fast but only over a short distance
Bus topology
one terminator Computers attached through out terminator
Adv and Dis of bus topology
Adv:
Inexpensive to install as less cable is used compared to star and no additional hardware needed
Dis:
If main cable fails networks can not be transmitted
Low security
Star topology
Has a central node(switch),acts as a router to transmit messages and keeps record of unique MAC address
Adv and Dis of star topology
Adv:
If one cable fails only one station is affected not the rest
Each cable is separate so no collisions of data
Easy to add new stations
Dis:
May be costly to install because of length of cable
If central goes down network can no longer be transmitted to nodes
What is a physical topology?
Its actual design layout
What is a logical topology?
The shape of the path the data travels in ,and describes how components communicate across the physical topology
When is a gateway used?
A gateway is used to transfer packets that do not share the same protocol
What is FTP?
File transfer protocol is an application level protocol used to move files across a network
Different part of a Packet
Header-contains recipient’s address so that it can be directed appropriately across the network
Payload-contains data)
Trailer-this checks any errors such as if the packet is corrupted during the transfer
What is a handshake?
The exchange of signals between two devices to signify that they are ready for communication.
protocols will be agreed on prior the communication.
Why is a handshake neccessary
It is necessary because without an agreement of rules the two devices cannot understand each other’s signals.
What is a simplex data transmission?
Communication is only ever in one direction
What is a duplex data transmission?
Can be in both directions simultaneously
What is a half duplex data transmission?
Can be in both directions but only one at a time
What is the world wide web
The WWW is a collection of webpages that reside on computers connected to the internet. It uses the internet as a service to communicate the information within these pages
TCP/IP; Application layer?
Application layer sits at the top of the stack and uses protocols relating to the application being used to transmit data over a network.
TCP/IP; Transport layer?
Transport layer uses the TCP to establish and end-to-end connection with the receipents computer
TCP/IP; Network layer?
The network layer adds the source and destination IP addresses Routers operate on the network layer and will use these IP addresses to forward the packets on to the destination
TCP/IP; Link layer?
The link layer is the Physical connection between network nodes and adds the unique MAC address identifying the NICs of the source and destination computers
An advantage of a client-server network?
Security is better since all files are stored in a central location and access rights are managed by the server
Backups are done centrally so there is no need for individual users to back up their data, if there is a breakdown and some data is lost, recovery procedures will enable it to be restored
An disadvantage of a client-server network?
It is expensive to install and manage
Profesional IT staff are needed to maintain the servers and run the network
An advantage of a peer-peer network?
It is cheap to set up
it enables users to share resources such as a printer or router
A disadvantage of a peer-peer network?
Used for online piracy
What is Authentication?
Most networks are protected by a username and password. These can be cracked
What are firewalls
Firewalls are various combinations of hardware and software that can isolate a network from the outside world.They are configurable to allow or deny access to certain addresses or certain types of data
What are proxies?
These are computers that are interposed between a network and a remote resource. They can react in a more sophisticated way to control input to an output from a network
