1.3.1 Flashcards
ISP
internet service provider is a company that provides you with access to the internet
URL
uniform resource locator is the web address of a website, it is a unique address
IP address
every hardware device connected to the internet has its own unique address, this address enables every device in the network to be identified
DNS
domain name server is the internet equivalent of a phone book
hosting
website has to be hosted n a web browser
steps for accessing a web page
- website is hosted in a webserver which as a unique IP address
2.URL is typed into the browser - browser send request to DNS server, DNS holds the website name and its corresponding IP address, the DNS gets the corresponding IP address
- if DNS cannot find the IP address, it passes a request to the higher DNS and if still not found it sends an error message
- the IP address is sent back to the browser, the browser uses the IP address to locate the server hosting website and sends a request to the webserver
- the server sends a copy of the webpage as packets which is then displayed on the browser
explain how the URL www.ocr.org.uk is converted into the IP address (3 marks)
The browser sends a request to the DNS server which holds its corresponding IP address and gets it. If DNS can not find the IP address it displays an error message. The IP address is sent back to the browser. URL sends it to DNS.
Network Interface Card
-every device on a network needs one
-each NIC has its own MAC (media access control) address
what does a MAC address do?
enables every device on a network to be uniquely identified which allows the data to be sent to the right device
Hub
-small box which links nodes together to form a network
-transmits data from one node to another, in the form of data packets
-when a data packet arrives at the hub, it is transmitted to every other node on the network
when a data packet arrives at the hub, it is transmitted to every other node on the network- why is this not efficient?
can cause data collisions
switch
-for larger networks or networks where security is important, a switch is a better option that a hub
-switch sends data packets only to intended node, switch reads the destination address from the data packet and sends it only to destination node
benefits of a switch
-security is improved
-lower risk of data collisions
router
-device which transfers data from one network to another
-without a router you would not be able to connect to the internet
-router needs data packets IP address
-router uses database routes to look up where IP address is
-identifies all of the different routes that could be used to reach the destination and sends the data packets down the fastest route
network cables
-used to join individual forms of LAN
-wired networks have a higher bandwidth than wireless
-cables used in LAN are ethernet cables, CAT-5 or CAT-6
-fibre optic cables are used to connect WANs together, they provide a high bandwidth and are able to cover a much larger distance
WAP and WiFi
-wireless access point (WAP) used to connect WiFi devices to a wired network without the need for cables
-WAPs commonly found in homes
-WAPs are similar to hubs, they do not need the MAC address of the destination packet- bandwidth is less
Hub in comparison to a switch
hub:-connects nodes on the network together, it is not intelligent
-data packets are transmitted to every node on the network
-higher risk of data collisions leading to slower network performance
-security risks because data is sent to all nodes
-less expensive than a switch
switch:-an intelligent device which connects nodes on the network together
-data packets are transmitted only to the node for which it is intended
-less risk of data collisions leading to improved network performance
-better security as data only sent to correct node
-more expensive than a hub
MAC address compared with IP address
MAC address:-cannot be changed, every device has a fixed address
-6 bytes long
-normally written in hex
-configured by hardware
-only used within the LAN (switch)
IP address:-can be changed (IPv4, IPv6)
-4 bytes long
-normally written in denary
-configured by software
-used for routing across a WAN / internet
topology
the way in which all parts of a network are arranged and connected together
-shows how data flows regardless of physical design
-includes the nodes (computers) and connecting lines (cables)
star topology
-server / central computer / switch is in the middles and cables run from the central device to each work station
advantages of star topology
-most common network layout
-fast connections
-faults are easier to trace
-relatively secure connections
-if the cable fails the other work stations keep working
-easy to add new workstations
disadvantages of star topology
-difficult to install
-expensive set up
-complex operating system
-server can get congested
-needs managing
-depends on the functioning of the central component
-if cable fails there is no other way of sending data from that workstation
mesh topology
-each node relays the data it receives to other nodes within reach
-there is no central node
-multiple paths between nodes
advantages of mesh topology
-data can be transmitted from different devices simultaneously
-highly robust
-can handle high volumes of data traffic
-adding or removing more devices will not hamper the transmission of data
-excellent for wireless networks
disadvantages of mesh topology
-expensive compared to other topologies
-self maintenance complex
-difficult to expand the network
-number of connections increases as more nodes are added
-impractical due to number of cables needed