Networks Flashcards
What is a symbol in communication?
A particular pattern of bits represented by a signal, e.g., 1110
What does Baud rate measure?
The number of signal changes in the medium per second.
What is the relationship between bit rate and Baud rate?
Bit rate = Baud rate x Number of bits per signal.
How is bit rate defined?
The number of bits transmitted over the medium per second, often measured in bits per second
What does bandwidth refer to in communication?
The range of frequencies that a communication medium is capable of transmitting, expressed in Hertz.
What is latency in communication?
The difference in time between an action being initiated and its effect being noticed, measured in milliseconds.
What typically happens to latency with increased distance?
Latency usually increases with distance.
What is a protocol in communication?
A set of rules relating to communication between devices.
What is serial data transmition
Data is sent one bit at a time along 1 line.
Used for long range communication
What is parallel data transmission
Data is sent along parallel wires one bit along each line
Advantages,
disadvantages of serial data transmition
ADV
Cheaper,no skew or crosstalk,more reliable.
DIS
Takes longer
Advantages,disadvantages of parallel data transmition.
ADV
More bits sent per second,
DIS
Data going to other branches (crosstalk), different times of output (skew), expensive.
Synchronous transition
A clock signal (shared by sender and reciever) data sent then.
Asynchronous transmition
Start,end bit is opposite.
Start bit tells driver clock to synchronise with sender clock.
Then data sent
Then end bit tells clock that the processor can then processor the data sent.
Physical network topology
Actual archtecture of a network.
Star topology
Clients have a connection to a Hub. Hub receives packets and send then to correct recipients.
Bus topology
Uses a single cable called a backbone. Terminators are at the end.
Logical network topology
This refers to the flow of data packets in a network.
Client-server nerworks
One or more servers provided services and the clients request the services from them and the server responds to them.
ADV
Security, central management,
DIS
Expert needed to make and manage
Peer-Peer networking
Services are provided by clients and are all equal. All have some importance and resources as shared and stored.
ADV
Cheaper,no powerful server,easy to set up
DIS
Security, if one doesn’t work nobody can use it.
What is packet switching
Packets are data that is sent over the network
The object is split into packets and then sent over the Internet by the router.
Every time it passes through a roster it counts as a hop.
What does a packet contain
Sender IP address
Recipient IP address
Time to live (number of hops)
Packet contents
Sequence number (the order of them)
What is a router
They send packets in the fastest way (lowest hops). They hold INFO about fastest routes and is usually updated.
What is a gateway
When 2 networks use different protocols.
It strips everything away leaving the contents. It then gives knew sending and recent addresses.
What is a URL
An address assigned to files on the Internet. Different protocols acces different files.
What is a FQDN
Is a domain that specifies an exact resource and interpreted in only 1 way.
What is a DNS system
It is a table of domain names and their corresponding IP addresses.
What is an Internet register
An organisation responsible for the allocation of IP address.
There in only 5 in the 🌎
What is a Fire wall
Sits between Internet and the device.
Filters through packets and does packet filtering and stateful inspection.
What is packet filtering
The firewall to accept/block packets based on IP address or the protocol.
What is stateful inspection
Examines the contents of packets before deciding whether to allow it through the firewall.
What is a proxy server
Sits between a public and private network. It manages the packets that pass through the network.
What is symmetric encryption
Both the the sender and recier share the same keys
The key is shared on the network and easily intercepted.
Asymmetric encryption
The digest is created by a hashing algorithm. This is determined by the message.
The digest changes if the message changes
They send the public keys to each other.
What is a worm
Pieces of malicious software that self replicate between computers.
Usually happens by downloading it or can be in a network.
What is a trojan
Is a type of malware that is hidden as a usefull file
What is a virus
These are usually files that are on computers and need to be ran to start replicating
it needs a host
What can we do to prevent malware?
Making sure code does not have errors
Make sure anti virus is up to date. And use it
don’t open sketchy stuff
What are the processes of TCP/IP stacks
APLICATION
Selects the correct protocol to transport the data.
TRANSPORT
Creates a virtual path that I’d from sender to the recipient. Splits it in to packets.
They have sequence numbers and TCP added on.
NETWORK
This layer adds the IP address of the sender and the recipient.
LINK
This ads the MAC address to the packets and controls the physical connections between pieces of hardware in a network.
What’s a socket adress
When an IP address is combined to a port number.
What is the well known port for FTP and what is this protocols used for?
Port 20 and 21
Used for sending files over the network
What is the well known port for HTTP/HTTPS and what is this protocols used for?
80 HTTP
443 HTTPS
This is used to hols Web pages.
HTTPS stop people with tampering with it.
What is the well known port for POP3 and what is this protocols used for
110 & 995
Used for receiving email.
What is an IP address split into
A network identifier and a host identifier.
What is it called when you beak a network into a smaller network
Subnets
If 255.255.255 is the subnet mask and the IP address is 192.168.3.24. What is the network identifier.
What is IPv4
