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computer science ocr a level > 1.3.3a and 1.3.3b networks > Flashcards

1.3.3a and 1.3.3b networks Flashcards

covers network characteristics and importance of protocols and standards. (b) internet structure: • The TCP/IP Stack. • DNS • Protocol layering. • LANs and WANs. • Packet and circuit switching (REFERENCE SOME STUFF FROM BOOK)

1
Q

what is a network

A
  • two or more computers connected together that transmit data
  • system that allows computer systems to communicate and share resources with each other
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2
Q

benefits of networks

A
  • share / work on same file and access files on any PC
  • share hardware resources (peripherals)
  • deploy software update from central location
  • centralised backup automatically carried out
  • 1 internet connection required which can be shared for all devices on a LAN
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3
Q

drawbacks of networks

A
  • can be hacked via internet
  • malware can spread very easily
  • expensive to set up (extra hardware required)
  • specialist knowledge required to set up
  • reliance on central server
  • increased security risks to data (now shared)
  • computers may run slower if amount of traffic is very high
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4
Q

what is a standalone computer

A
  • a single computer / device not connected to any other devices or networks
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5
Q

what is a LAN

A
  • local area network
  • small geographical area located on single site
  • use own infrastructure
  • connected with switch and UTP cables
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6
Q

what is a WAN

A
  • wide area network
  • large geographical area
  • connects LANS
  • infrastructure leased by third-party communications
  • connected with routers
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7
Q

what is a standard

A
  • set of hardware and software specifications that allow manufacturers to create products and services that are compatible with each other
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8
Q

why is ethernet a standard

A
  • both remote networks need to set same rules regarding way packets transferred across network
  • allows compatibility between devices
  • high bandwidth, reliable and cheap
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9
Q

a key way of ensuring technology based standards are established and adhered to are by the use of what?

A
  • protocols
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10
Q

what is a protocol

A
  • set of standards that govern the communication between 2 devices
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11
Q

give 3 communication protocols

A

TCP - Transmission Control Protocol
IP - Internet Protocol
UDP - User Datagram Protocol

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12
Q

give 2 web-page request protocols

A

HTTP - Hypertext Transfer Protocol
HTTPS - Hypertext Transfer Protocol Secure

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13
Q

give a file transfer protocol

A

FTP - File Transfer Protocol

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14
Q

give 2 email (receiving) protocols

A

POP - Post Office Protocol
IMAP - Internet Message Access Protocol

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15
Q

give an email (sending) protocol

A

SMTP - Simple Mail Transfer Protocol

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16
Q

what is the Internet Protocol (IP)

A
  • Internet Protocol (IP) is a communications protocol responsible for routing data packets across a WAN using IP addresses
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17
Q

IP works alongside what protocol to make what protocol stack

A
  • IP works alongside TCP to make the TCP/IP protocol stack.
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18
Q

what is the TCP/IP protocol stack.

A
  • set of networking protocols consisting of 4 layers working together
  • all incoming and outgoing data packets pass up and down through the various layers
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19
Q

what is TCP

A
  • Transmission Control Protocol
  • provides error free transmission between 2 routers
  • does splitting of packets, labelling each with packet number and error checking of packets (can request for packet retransmission)
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20
Q

what is UDP (User Datagram Protocol)

A
  • uses a simple, connectionless transmission model. used to send short messages using datagrams where speed is more important than accuracy
  • maintains an open, 2-way connection ideal for online gaming
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21
Q

UDP is an alternative option to TCP. What is the difference between both?

A
  • UDP has no error checking so less reliable than TCP
22
Q

what is HTTP

A
  • way for client and server to send and receive requests ad deliver HTML web pages
  • fundamental protocol of World Wide Web
23
Q

HTTP runs on what architecture? ( hint what is the client and what is the server)

A
  • runs on a client–server architecture
  • web browser = client (requests web pages and linked resources from web server)
  • client can also send limited data back to web server as user interacts with web page.
24
Q

difference between HTTP and HTTPS

A
  • HTTPS adds SSL encryption and authentication
25
Q

when should HTTPS be used

A
  • whenever website deals with sensitive info like passwords and bank details
26
Q

what is FTP

A
  • used for sending files between computers normally on a WAN
27
Q

what are FTP clients

A
  • software applications that sit on top of actual FTP protocol
  • when you interact with the software, client generates and sends appropriate FTP commands
28
Q

what can mail servers be thought of as

A
  • a virtual post office handling incoming and outgoing email
29
Q

what is SMTP

A
  • transfers outgoing emails between servers and from email clients to servers
30
Q

what is POP

A
  • Post Office Protocol retrieves emails from mail server and transfers them to your device, in ding so removing them from server
31
Q

what is IMAP

A
  • keeps emails on mail server, maintaining synchronicity between devices
32
Q

what is the similarity and difference between POP3 and IMAP

A
  • POP3 and IMAP are the protocols used to retrieve the emails.
  • POP3: downloads them onto client device + deletes emails from server
  • IMAP creates copies on local client device and synchronises any deletion on both client + server.
33
Q

why is IMAP more favoured

A

IMAP is the preferred protocol because it offers the ability to manage your emails on multiple devices.

34
Q

what is the internet

A
  • collection of interconnected networks, routers, cables, satellites and other hardware spanning the world
  • WAN
35
Q

when transmitting data between routers over a WAN, what happens to the MAC address

A
  • MAC address is changed at each hop on the route
36
Q

in terms of addressing a letter, what analogy can be made for the distinction of MAC and IP addresses

A

similar to how we would address letter:

  • MAC address tells me who you are
  • IP address tells me where you are
37
Q

a host may need to broadcast first if it doesn’t already know the destination MAC address. What protocol helps to achieve this

A
  • ARP (Address Resolution Protocol) which is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address.
38
Q

what happens as traffic passes through a switch

A
  • switch examines source and destination MAC addresses and learns which address applied to which device eliminating need for broadcasting
39
Q

fill the gaps:

modern routers are both ________ and _________, performing both ___ switching and ___ routing

A
  • routers
  • switches
  • LAN
  • WAN
40
Q

NIC Card’s Manufacturer provides the what?

A

MAC address

41
Q

Internet Service Provider provides the what?

A

IP address

42
Q

what is the World Wide Web

A

collection of files with info stored in hypertext (web pages) and other associated files, hosted on web servers

43
Q

what do web servers host and also what do they handle

A
  • host (store) the files and handle client requests (e.g. HTTP GET request for a page / resource)
44
Q

purpose of a router

A
  • directs packets across network to destination
  • receives + forwards packets
  • maintains routing table
  • identifies most efficient pathway
  • assigns devices IP addresses
  • connects different networks (home to internet)
  • has public IP address for LAN
  • designates private IP addresses to network nodes
45
Q

what are edge routers

A
  • Edge routers  link one network to another.
46
Q

describe 2 types of edge router

A

Subscriber routers:
 - routers provided to homes + small businesses. - small scale, low-cost devices with two interfaces (one for each network).

Enterprise routers:
- connect large businesses and ISP networks to internet.
- far more powerful + expensive and are capable of handling very high volumes of data.

47
Q

what is a core routers 

A
  • Core routers  are the routers that are part of the internet backbone.
  • These routers have multiple interfaces, all of which can work at the highest speed simultaneously.
48
Q

what is a switch

A
  • interconnection device connecting 2 or more devices. helps solve data collision issues.
  • packets arrive at switch, destination address examined + switch creates direct connection to device so traffic goes where intended
49
Q

what is a data collision

A
  • 2 or more devices sending packets onto network simultaneously
50
Q

what is packet switching

A
  • process of sending / forwarding received packets across a network.

TCP splits up and sequences packets for transmission. IP simply routes them to their destination.

Packet switching is a routing method for data whereby the data is split into chunks (packets) which have labelled identifiers (payload and the header which store address packet is being sent to and the order number of that packet to reconfigure at the end).Each packet is routed by the router on the most efficient/convenient route. This means that they arrive in a different order to which they were sent. Once all packets reach destination determined by metadata the packet has stored, they are reordered to for the data at the destination.

51
Q

Describe the DNS process (simple detail)

A
  1. user requests a URL via a browser
  2. browser sends the domain name to the domain name system
  3. the DNS maps the domain name to an IP address and returns it to the browser
  4. a get request for the web page is sent to the web server using the IP address
  5. the web page is returned to the clients web browser
52
Q

Explain the DNS Process (requires more detail)

A
  • the URL is input into the browser and sent to DNS resolver server
  • the URL is received by a DNS resolver server
  • the server then queries the DNS root server
  • the root server responds with the address of the top-level domain server for eg .com
  • the resolver then makes request to .com top-level domain server
  • this specific TLD responds with the IP address of the domain name server like google.com
  • the IP address is then returned to the resolver
  • the DNS resolver responds to the web browser with IP address of google.com

computer science ocr a level (17 decks)

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