1.3.3 - Networks Flashcards

Question

What is layering?

Answer 1

Is a form of abstraction. Division of a complex system into its component parts. Allows work to be carried out piecemeal. Each layer communicates only with adjacent layers. Allows efficient problem solving – focusing on one part of the problem in isolation.

Answer 2

Are unique identifiers associated with a network interface. They: - provide addressing capability in a network. - are usually assigned by the manufacturer. - are 48-bit (6-byte) addresses, i.e. 6 octets, e.g. DC-85-DE-4B-FB-3A

Answer 3

File is divided or split into equal groups of bits of standard size made up of control bits and data. Have a structure defined by the protocol being used. Each has an identity on the label attached stating the following. There are 3 basic parts: Header: - Sender’s/ transmitting IP address - Receiver’s/destination IP address - Protocol being used - Packet number and order, i.e. the place of the packet in the complete message Payload: - The data file to be transmitted Trailer: - End of packet marker - Error correcting code

Answer 4

There are three phases: - connection establishment - data transmission - connection termination. Physically connects devices together - so-called ‘connection mode’. Devices remain connected for the duration of data transmission. Establishes a route before transmission between the two computers for the duration of the message. Ties up large areas of network so no other data can use any part of the circuit until the transmission is complete. Sends all packets on the same reserved route down the circuit in order. Message can be interpreted if the route is tapped into. Packets remain in correct order but must be reassembled at the destination.

Answer 5

Central to the success of the internet. Is connectionless mode, i.e. no permanent connection is established for the message. Has no established route or pre-set path. At each node on the network the destination address is read and the best available route is found from source to destination This means individual packets being sent on to the network on the most convenient or avoidable paths. Transmission is safer from interception and avoids message failure if a route is disrupted because it is impossible to intercept all packets as they use different routes so is more secure. Packets arrive out of order at the receiving end and need to be reordered and message is reassembled to recreate the data at its destination. Only as fast as the slowest packet. Maximises use of the available infrastructure very efficiently as each channel is only used for a short time so does not tie up a proportion of the network. Loss of part of the communication will not be fatal because if there is an error then only a small, identifiable, part of the data or one packet is affected which can be retransmitted easily if the message does not arrive safely. Error checking promotes successful transmission.

Answer 6

Are anti-hacking applications (hardware and/or software) that sit between the system and external access to control traffic signals and into and out of a network, ensure communications are restricted and attempt to limit or prevent access to the system by particular unauthorised sources, systems, users or external machines.

Answer 7

Is a computer placed between a network and a remote resource that intercepts traffic and restricts the users allowed access to individual machines on network from in the internet to isolate the network from the outside world.

Answer 8

Attacks send requests from multiple users, or bots, to disrupt the service for political reasons or simply to blackmail the service owner/provider.

Answer 9

Routers Switches Hubs WAPs NICs Cables Modems Gateways

Answer 10

Responsible for routing data between devices, connecting at least two networks together (like connecting a LAN to your ISP). Works as the network layer.

Answer 11

Alters the signal between A and D to act as a gateway to the WAN Works at the physical and data link layers. (connect to the outside world, and to connect router via ethernet)

Answer 12

A communications device that enables a computer or device that does not have built-in networking capability to access a network. There is a wireless and a wired version. Works at the physical and data link layers.

Answer 13

A switch that allows devices to connect wirelessly Is usually connected to a router. Works at the data link layer.

Answer 14

A hub is a networking device, that allows devices to connect to a network. Broadcasts the signals they receive to all connected computers, unlike a switch, which only sends data to the intended recipient. This greatly decreases network performance due to the amount of transmissions.

Answer 15

A switch is a network device which creates a *separate collision domain on each port*, while remaining within a single broadcast domain. Much faster than hubs due to device having an individual port for a device.

Answer 16

Fibre optic - Glass fibres, fastest bandwidth but are expensive, longest distant connections. Twisted Pair - Copper wiring, but low bandwidth Coaxial - 4 components, faster bandwidth but are more expensive than twisted pair

Answer 17

File transfer Protocol Used to access, edit and move files between devices on a network (e.g. to access files on a server from a client computer)

Answer 18

Post Office Protocol 3 Used to retrieve emails from a server. The server holds the email until you download it, at which point it is deleted from the server

Answer 19

Internet Message Access Protocol Stores the message on a server and synchronizes the message across multiple devices.

Answer 20

Simple Mail Transfer Protocol Used to send emails. Also used to transfer emails between servers.

Answer 21

HyperText Transfer Protocol/ Secure. Uses encryption for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protocol is encrypted using Transport Layer Security

Answer 22

A server controls: -Access and security for a shared file store -Manages access to the internet -Manages printing jobs -Provides email services -Runs regular backups of data A client makes requests to the server for data, connections and other services.

Answer 23

All computers are of equal status. Computers can act as a client or server, or both. Useful on the internet so traffic can avoid servers. Is private so there isn’t a reliance on the company’s server and its connection to the Internet. This means it hasn’t got to invest in lots of expensive hardware and bandwidth so is cheaper. The system is likely to be more fault tolerant.

1.3.3 - Networks Flashcards

(48 cards)