Networks 1 Flashcards
What is a
network?
an arrangement of two or more computers that are connected for the purpose of sharing resources and data
What do networks allow multiple users to do?
- share data files with each other
- share hardware devices
- share an internat connection and internet services, such as the world wide web and email
- comunicate with each other, using services such as email and messaging
- work together using web-based software, virtual meetings, shared calendars, etc
What are the key characteristics of
LANs?
- small geographical area
- owned by private individuals
- more secure
- slower cables but few users
- less expensive as less hardware is required
What are the key characteristics of
WANs?
- large geographical area
- owned by businesses and organisations
- less secure
- faster cables but shared amongst millions of connections
- more expensive
- mesh network
Describe a
bus topology.
All the nodes on the network are connected to a single cable, known as the backbone. Messages are sent along the cable in the form of electronic signals. A terminator at each end absorbs signals that have reached the end of the cable, preventing them from bouncing back.
What are the advantages of a
bus topology?
- relatively cheap to install since very little cabling is needed
- if one node fails, the rest can still communicate with eachother
- very easy to add extra devices to the network
What are the disadvantages of a
bus topology?
- if the cable is cut or damaged, the whole network stops functioning
- more collisions will occur with more devices and the network will run slower
- all nodes on the network ‘see’ all data traffic, this may be a security risk
Describe a
star topology.
Every node is directly connected to a central node. All data traffic passes through the central node, which is responsible for routing it to its destination.
What are the advantages of a
star topology?
- if one node goes down, the rest of the network will continue functioning
- a damaged cable doesn’t stop the network from working, just the device connected to it
- data traffic is only sent to the intended recipient, this makes it secure
- it is easy to locate faults because they normally only involve one node
- nodes can be added and removed without having to take the entire network offline
What are the disadvantages of a
star topology?
- if the central node fails, then the rest of the network stops functioning
- network performance depends on the capacity of the central node
- a lot of cabling is required, making it difficult and expensive to set up
Describe a
mesh network.
each node is connected to multiple other nodes
in a fully connected mesh network, every node is connected to every othe node
in a partially connected mesh network, some nodes are connected to all nodes while other nodes may only be connected to one or two others
What are the advantages of a
mesh network?
- very fault tolerant, if one node fails, messages are rerouted
- nodes can be added and removed without having to take the entire network offline
- very scalable, any number of additional nodes can be added
- very high performance because each network node is connected to multiple other nodes
What are the disadvantages of a
mesh network?
a fully connected wired mesh network is difficult and expensive to install
What is the
internet?
A shortening of the words ‘inter’ and ‘network’ which together mean interconnected network. It is a network of networks that is not owned by any single organisation or government.
Describe the
structure of the internet.
- Every device connected to the internet is part of a network.
- Local networks connect to the internet via a point of presence (POP) provided by an internet service provider (ISP).
- The ISP’s network is connected to a high-level network owned by a major telecommunication company, such as BT. Each of these companies has its own dedicated internet backbone.
- Network access points (NAPs) interconnect the internet backbones to form a worldwide (partially connected) network.
Routers forward data from one network to another across the internet from source to destination.
What is an
IP address?
A set of rules governing data transfer on the internet known as internet protocol.
Every internet-connected device is allocated an IP address.
IP addresses are used to uniquely identify devices on a network.
What are the
two versions of IP?
IPv4 and IPv6
How can you identify
IPv4?
IPv4 uses 32 bits.
Each of the four bytes is expressed as a decimal number between 0 and 255 seperated by dots.
e.g. 192.168.182.42
How can you identify
IPv6?
IPv6 uses 128 bits.
An IPv6 address consists of eight 16 bit hexadecimal numbers seperated by colons.
e.g. fd2a:1450:4013:c01:0:0:0:5e
Why are IP addresses temporarily allocated to devices whilst they are connected to the internet?
to facilitate routing across the internet by providing a sender & destination unique addressing scheme
What is included in the header/metadata of an IP packet?
- IP address of source
- IP address of destination
- sequence number of packet
- total number of packets
- checksum
What is a
static IP address?
an IP address which never changes and is assigned to devices that require constant access to the network
(e.g. routers, servers)
