The internet Flashcards
1
Q
What is the internet
A
A network of networks that are Inter-Connected networks
2
Q
how are devices on the internet uniquely identified
A
an ip address
3
Q
Describe IPV4
A
IP version 4, addresses are made up of four octet values ( numerical values described by 8 bits) separated by a full stop
4
Q
What is A FQDN
A
A fully qualified domain name can be broken down into constituent parts including a host name, and the domain name itself.
www.example.com
5
Q
what is bbc.co.uk
A
the domain name
6
Q
what does URL stand for
A
Uniform resource locator
7
Q
what does www. do
A
specifies the host
8
Q
what would be the FQDN for the bbc
A
www.bbc.co.uk
9
Q
what is the url made up of
A
the protocol and the domain name of the resource together form the URL.
10
Q
what does DNS servers mean
A
Domain Name System- servers are dedicated computers with an index of domain names and their corresponding ip addresses.
11
Q
Describe the process of resolving an ip address (7 steps)
A
1st URL request by browser from a user
2nd Browser extracts the FQDN and sends it to a dns server
3rd Local dns server maps the FQDN to ip address and returns it to browser
4. If local DNS doesnt have the request is moved to the Regional DNS. (has a much larger look up table)
5. Unlikely event Regional DNS doesnt have it it mvoed to NSP (network service provider)
6. Ip is sent to browser and GET request is sent to web server.
7. File is returned to web browser
12
Q
Simply put what is the TCP IP protocol
A
A set of protocols that support network communication
13
Q
what is the purpose of the dns system
A
domain name system resolves names to ip addresses
14
Q
Why do websites have both domain names and ip addresses
A
hard to remember ip
IP address required for computer to access the site.
15
Q
Describe the process of packet switching (6 steps)
A
Messages are split into packets
Each packet is given a destination and source address
Packets are given a sequence number
Each packet in independently dispatched to the Internet through a router gateway
Routers forward packets to other nodes on the network until they reach destination
Packets reassembled at the destination
16
Q
What is a router
A
Connects two networks together
Determines which node to send a packet to next
17
Q
Describe the process of Routing (3)
A
Routers forward data packets from one network to another
Each router stores data about the available routes to the destination node
Routers are organised in a hierarchy
18
Q
What does the header of a packet contain (4)
A
destination address
source address
the packet (sequence) number and number of packets
the Time To Live
19
Q
What are the 3 parts of the data packet
A
Trailer payload header
20
Q
What does the payload contain
A
At its core, a data packet is a segment of data that needs to be sent, often referred to as the payload
This part of the packet will often vary in size from 500 to
1,500 bytes
Payload refers to the actual data being sent in the packet
21
Q
What does the Trailer/Footer contain
A
A packet trailer / footer contains error checking components that verify the data has not been corrupted on transfer
Techniques such as checksums are used to check the data by the receiving host
The same checksum is recalculated at the destination
If they do not match, the data has become corrupted and is refused and a new copy is requested to be sent again
22
Q
What is a gateway when is it required (2)
A
A gateway is required where data is travelling from one network to another that use different protocols
Networks using different transmission media can require this
A router and gateway can often be combined into one integrated device
23
Q
Describe how a gateway operates
A
Header data are removed and reapplied using the correct format of the new network
24
Q
Describe what is meant by the Time To Live data in a data packet.
A
a maximum number of hops a packet can take to reach its destination
25
why are packets a certain size
small enough to ensure individual packets do not take excessive time to transfer
However, they should not be too small as the additional data added makes data transfer inefficient as unnecessary headers and trailers would be required each time
26
Example gateways
Examples include connecting a LAN to the Internet, or connecting different types of internal networks
27
describe what happens to the data packet at a gateway
header is removed and reapplied using the correct format of the new newtork.
28
What is the point of the application layer of the TCP/IP Layer (2)
The application layer uses an appropriate protocol relating to the application sending data.
For websites this would be http
29
How is the transport layer of the TCP/IP Model used (4 parts)
Uses TCP protocol
establishes end to end connection
splits data into packets.
adds sequence number and port to packets.
30
How is the network layer of the tcp/ip layer used (4)
Uses the internet protocol (IP)
Adds source IP destination IP addressses to packets
Performs routing
Creates checksum for the packet.
31
How is the link layer of the TCP/IP used
Adds mac address of source device and destination device to the packets of data.
32
What happens at the link layer when receiving data
removes the MAC addressfrom each packet and passes it to the network layer
33
What happens at the network layer when receiving data (2)
The network layer removes the ip address from each packet
and then passes it to the internet
34
What happens at the transport layer when receiving data (3)
The transport layer removes the port number from each packet,
reassembles the packets in correct order
and passes them to the application layer.
35
What happens at the application layer when receiving data
The Transport Layer delivers data packets to the appropriate application.
36
Describe how a port number is used
A port is used to alert a specific application to deal with data sent to a computer
These are used by protocols to specify what data is being sent
37
What are the two types of port numbers
Well known port numbers
Client port numbers
38
what are well known port numbers
A reserved port number that has a specific purpose assigned by the Internet Assigned Numbers Authority (IANA)
39
what are client port numbers
Temporary port numbers that are assigned by the transport layer to the network application on the client computer.
40
What is Secure Shell
An encrypted protocol that allows secure communication between nodes across a network.
41
What does SSH stand for
Secure Shell
42
Why was SSH invented, and what are its functions
As a protocol used to securely connect to and manage devices or servers over an unsecured network, such as the internet.
It provides encrypted communication and ensures confidentiality, integrity, and authentication during data transfer
43
What are the key features of SSH ( 6)
Encryption
Authentication
Port Forwarding
Secure Remote Access
Command execution
File transfer
44
What protocols are used for sending an receiving emails
SMTP
POP3
IMAP
45
Explain SMTP
Used to send emails and forward them between mail servers to their destination
46
Explain POP3
Downloads emails stored on a remote server to a local client(removed after download)
47
Explain IMAP
Manages emails on a server so multiple clients can access the same email account in synchronicity
48
What is a firewall
A firewall is either software or hardware that controls access to and from a network
49
How does a firewall operate
A firewall is either software or hardware that controls access to and from a network
Data packets from specific IP addresses can be filtered
Data packets also have ports which can be used to only allow traffic through from certain port numbers.
50
Describe packet filtering
Packets of data are inspected by the firewall to check their source IP address and which port they are attempting to access to decide whether to allow them through
51
What is a proxy server
A proxy server makes a web request on behalf of your own computer, hiding the true request IP addresses from the recipient
52
What are the functions of a proxy server(4)
Enables anonymous surfing
Can be used to filter undesirable online content
Logs user data with their requests
Provides a cache of previously visited sites to speed up access
53
four different ways that a firewall can protect computers on a LAN
Block/allow traffic on specific ports
Block/allow traffic from specific IP addresses
Block/allow certain types of packet
Firewall maintains information about current connections and only allows packets relevant to these connections through
54
Definition of encryption
The act of encoding a plaintext message so that it cannot be deciphered unless you have a numerical key to decrypt it.
55
What is meant by symmetric encryption
Symmetric encryption uses the same key to encrypt and decrypt the data being transferred
56
What is asymmetric encryption
Uses two separate, but related keys
57
What is a popular and secure way for generating a key pair for asymmetric encryption
One way of achieving this would be by using the RSA algorithm.
58
Describe the steps of asymettric encryption
recipients public key is made available
The recipient’s public key is then used to encrypt the data before sending
The encrypted message is sent
The recipient’s private key is used to decrypt the message
59
Summarise the Digital Signature Creation and Encryption process on the sending and receivin end( 7steps)
Hashing: The sender computes a hash (digest) of the message using a hashing algorithm.
Signing: The sender encrypts the hash using their private key, creating the digital signature.
Encryption for Recipient: The sender bundles the digital signature with the message and encrypts the bundle using the recipient’s public key.
ON the receiving end:
Message is decrypted with recepients private key
digital signature is extracted and decrypted with senders public key copy
plaintext message has hashing algorithim reapplied and compared to the digital signature
If they are the same it means we can verify it is the real sender who sent the message.
60
Describe the digital signature decryption process (3steps)
Decrypt Bundle: The recipient uses their private key to decrypt the message and digital signature bundle.
Verify Signature: The recipient decrypts the digital signature using the sender’s public key, revealing the hash (digest) created by the sender.
Hash Comparison: The recipient computes their own hash of the received message and compares it with the sender's hash:
61
What makes a digital signature unique
As a signature can only be decrypted by the sender’s public key the signature can be considered genuine and unaltered
62
What is another name for the hash that is produced from the hash algorithm and forms the digital signature?
Digest
63
How does a digital signature check if a message has been tampered with ( 4 steps)
Hash of the Original Message: The sender computes a hash of the message and encrypts it with their private key to create the digital signature. This hash uniquely represents the original message's content.
Recipient's Hash: When the recipient receives the message, they compute their own hash of the received message using the same hashing algorithm.
Decrypted Signature Hash: The recipient decrypts the digital signature using the sender's public key, revealing the hash originally created by the sender.
Comparison: The recipient compares their hash (from the received message) with the decrypted hash (from the signature):
If the hashes match, the message has not been altered.
If the hashes do not match, the message was tampered with after being signed.
64
What does a digital signature often come with
they also send their digital certificate
A trusted company known as a Certificate Authority (CA) provides this, which includes:
a serial number
name of the CA
expiry date
65
What are viruses
A program that attaches itself to or conceals itself within another program / file
It is self-replicating
Has malicious purpose such as deleting files, hiding files
66
What is TLS encryption
(Transport Layer Secure) encryption
A protocol that secures communication over the internet by encrypting data exchanged between devices
67
What does TLS encryption prevent
Prevents eavesdropping, tampering, and data theft during transmission.
68
What are worms
A worm is a standalone program that does not require a user to run it in order for it to spread.
They exploit vulnerabilities in the destination system and spread automatically.
69
A file is being transferred between two computers across a network using a file transfer application.
Identify a protocol that could be used to transfer this file
File Transfer Protocol
70
What is trojan horse
Trojans are malicious pieces of software that masquerade as something seemingly innocuous or useful
They cannot self replicate
Often they server to open up back doors in your computer to the internet so that the processing power, internet bandwidth and data can be exploited remotely.
71
How can we reduce threats from malware (5)
improve code quality
Monitoring attempts, protection
Guarding against buffer overflow attack
Use of strong passwords for login credentials.
2FA
72
What is buffer overflow
Buffer overflow occurs when a program accidentally writes data to a location too small to handle it.
73
What is sql injection
A malicious user can enter SQL commands via online database forms to change the processing.
74
What is a ip address
a unique numerical address which identifies a host computer of a network.
75
Describe IPv4 makeup
Uses four octets each octect made up of a byte.
76
what is the last address in a network used for
is reserved as the broadcast address on that network for sending data simultaneously to all hosts on that network
77
What is a host
any computer on a network that can use the internet
78
What is 127.x.y.z
is reserved for loopback in which a hosts ip software treats an outgoing packet as incoming
79
what are the address range of IP's that are private addresses for LANS or private WANS
10.x.y.z, 172.16.0.0 to 172.31.y.z and 192.168.y.z
80
How many devices does IPv4 provide for
2^32 4.3 billion addresses
81
What are the two parts that make up IP's
Network identifier
Host identifier
82
Describe the host identifier
Right hand bits of 32 bit number used to identify seperate nodes on the network
83
Describe the network identifier
left hand bits of 32 bits number used to define the network where the nodes are communicating.
84
What is classless ip addressing
The use of a suffix such as /24 enables IP addresses to be used with varying proportions of network ID and host ID
85
what is a subnet mask
a number that identifies the network and host portions of an IP address
86
How is a subnet mask used
The subnet mask is used together with an IP address.
The subnet mask has all network id bits set to 1 and all host ID bits set to 0 so that, when compared to the IP address using a bitwise and operation, the network is identified.
87
How do computers with private ips address receive and send data on the internet
They must communicate via another network device that provides a network address translation, this allows a single public ip address
88
describe the operation of the NAT
This allows a single public IP address to be shared by any number of hosts with private IP addresses
This system is normally part of the router.
It keeps track of which private host is making requests on the internet
It then makes sure that when it receives the response from the internet, it sends it back to the private host that made the request.
The translation device records the source and destination socket addresses for each request
It then communicates on the host’s behalf with the destination IP address
When a response returns, it is passed back to the host that made the original request
89
What is port forwarding
Routers can be programmed so that requests with a particular port number can be automatically forwarded on to a device with a specific IP address within the network
90
Describe port forwarding (4)
A device on the internet sends a request to a public IP address on a specific port.
The router receives the request and checks its port forwarding rules.
If a rule exists, the router forwards the request to the internal device (private IP).
The internal device processes the request and sends a response back.
91
What is the DHCP
Dynamic host configuration protocol is used to automatially allocate ip addressses and other network configuration information to hosts
92
What does the DHCP allow (3)
Allows limited pools of dynamic ip addresses to be shared out between hosts and freed up when not needed.
allows hosts to reconfigure themseleves when moving between networks
reduces the number of ip addressses required locally as not all hosts need a static IP address.
93
What are the 4 steps involved in the DHCP
DHCPDISCOVER - request ip
DHCPOFFER - DHCP offers an avaiable ip
DHCP REQUEST - Broadcast confirm ip request
DHCPACK - acknowledgment and assignment
94
What is the purpose of the DHCP
To automate the configuration of hosts connecting to a (TCP/IP) network
To allocate IP addresses to hosts
95
What are internet registers
These are five global organisationsorganizations responsible for managing and distributing IP addresses
96
How is the domain name hierarchy ordered by
Generic Top level domains, Country TLD's, 2nd Level Domains, 3rd level domains
97
What are the functions of a router (3)
Uses the most efficient path to the destination
Monitors the network and updates its routing table to reflect congestion/network changes
Modifies the MAC addresses for the next hop
98
how are client ports and well known ports used when retrieving a web page
client port allocated to web browser by transport layer
Web servers typically use well-known ports to make it easy for clients to locate and connect to them for initiating communication
99
A section of the company firewall log is displayed on the accountant’s computer.
Firewall blocked access to resource at 84.134.4.128:80
Firewall granted access to resource at 84.134.4.128:22
From the log above, give an example of the following:
Port number
80
100
What layer of the tcp/ip protocol do routers operate at
Network layer
101
A section of the company firewall log is displayed on the accountant’s computer.
Firewall blocked access to resource at 84.134.4.128:80
Firewall granted access to resource at 84.134.4.128:22
From the log above, give an example of the following:
IP Address
84.134.4.128
102
A section of the company firewall log is displayed on the accountant’s computer.
Firewall blocked access to resource at 84.134.4.128:80
Firewall granted access to resource at 84.134.4.128:22
From the log above, give an example of the following:
Socket
IP + PORT NUMBER
103
What can be used to verify the owner's public key and ensure it is trustworthy?
digital certificate
104
What are items of data normally found on the digital certificate
Certificate authoriser info
Public Key
Public Key Algorithm
serial number
105
What is MAC address
A 6 byte unique identifier inscribed on a devices NIC by a manufacturer
106
What is meant by an API
application programming interface - a set of rules that allow software applications to communicate with each other
107
What is a server side API
is a set of web services or web resources to enable programmers to build web applications
108
What is it called when programmers use multiple server-side web APIs to create combined web applications
mashups
109
What is a websocket protocol
a communication protocol that enables real-time, two-way data exchange between a client (like a web browser) and a server over a single connection
includes an API for establishing a persistent TCP socket connection
110
Describe the features of the websocket protocol (3)
Connection is full-duplex (simultaneous two-way)
Allows client and server to send data at any time
Server can offer (“push”) data to the client
WebSocket Secure is encrypted
111
What are the two widely used formats for the standardised data objects that server and client can both process:
JSON
XML
112
Describe XML
XML - Extensible markup language has a format similar to HTML and wraps content in tags
113
Describe JSON
JavaScript Object Notation is written in a standard programming form, similar to JavaScript, and can be directly used by JavaScript
114
What are the advantages of JSON(3)
Easier for a human to read, write and mantain
More compact so requires less storage and quicker to transmit and process
Can be directly manipulated by java script
115
What are the disadvantages of JSON
works with a limited range of data types
116
What are the advantages of XML
Any data type allowed so more flexible
117
What are the disadvantages of XML
XML documents tend to be large due to excessive tags, which increases storage and transmission costs.
Also makes it more difficult to follow
118
What are features of the thick client architecture
Applications are installed locally on the thick client
119
What are the features of thin client architecture
applications arent installed locally, or only a light version of the application installed.
Processing is done on a powerful central server and the hosts are only used to display the results and provide user input.
120
What are the advantages of thin client computing (3)
Easy to set up, maintain and add clients
Server software and updates can be automatically distributed to each client
More secure because Security updates, patches, and antivirus can be centrally managed.
121
What are the disadvantages of thin client computing (3)
Reliant on the server
Requires a very powerful, and reliable server
Server demand and bandwidth increased
122
What are the advantages of thick client computing (3)
Robust and reliable - because the machines are more powerful and have more ram and processing speed.
Can operate without a continuous connection to the server
Generally better for running more powerful applications
123
What are the disadvantages of thick client computing (3)
Higher specification client computers required
Installation of software required on each client separately
Integrity issues with distributed data
124
What is http communication
HTTP communication refers to the exchange of data between a client and a server using the HyperText Transfer Protocol (HTTP).
125
what does http communication allow for
It is the foundational protocol of the World Wide Web, enabling the transmission of resources such as HTML files, images, videos, and other content over the internet.
126
What is the benefit of websocket protocols smaller packets. (3)
WebSocket packet sizes are greatly reduced without the usual headers
This in turn creates a superfast, interactive connection commonly used with websites requiring real-time updates
Server load is reduced, saving bandwidth and running costs as well as reducing the number of web servers required
127
What are the 4 basic web application functions
Create – write a record to a database
Retrieve – retrieve a record from a database
Update – amend a record
Delete – remove a record from the database
128
What are the HTTP request methods (4)
GET – request data from a source
POST – submit data to be processed
PUT – uploads a new resource to the server
DELETE – removes a resource from the server
129
What is the Representational State transfer
REST is an architectural style which determines how systems communicate with each other
130
Describe the operation of the REST architecture style
Client-Server Architecture
Stateless Communication
Use REST operations CRUD with equivalent HTTP methods Post,Get,Put,Delete
131
Which IP address is used to send a DHCP discover message broadcasts?
sent as a broadcast using the destination IP address:
132
Which layer of the TCP/IP protocol stack can be described as, 'where the network hardware such as the network interface card is located'?
Link/Physical
133
Which protocol is a client-server method of requesting and delivering web pages?
HTTP
134
Which IP address is used to send a DHCP discover message broadcasts?
255.255.255.255
135
What is the purpose of the TCP protocol
ensures reliable, ordered, and error-checked delivery of data between devices over a network.
136
DHCP servers are responsible for allocating what type of IP addresses?
dynamic
137
Which IPv4 address is reserved as a broadcast address on a subnet?
x.x.x.255
138
What are the advantages of the client server model (5)
Centralized Management
Better Security
Scalability
Data is stored in one place, reducing inconsistencies
Clients can access shared resources
139
Which standard protocol is usually assigned to port 80 & 8080?
HTTP
140
Describe the operation of a proxy server (5)
Client Sends Requests
Proxy Server Processes the Request
Proxy Forwards the Request to the Internet
Server Responds & Proxy Handles the Response
Proxy Sends Data Back to the Client
141
What is the purpose of the FTP protocol?
Transfer of computer files between a client and a server on a computer network
142
What is the standard port number assigned to File Transfer Protocol (FTP) control instructions?
21
143
Which IPv4 address is reserved as a private, non-routable addresses used for diagnostics within LANs?
127.x.x.x
144
What type of server uses POP3, SMTP and IMAP?
Mail server
145
Which standard protocol is usually assigned to port 443?
HTTPS - Hyper Text Transfer Protocol Secure
146
What does the IP protocol do?
routes packets between two routers.
147
Which IPv4 address is reserved as a private, non-routable addresses used for diagnostics within LANs?
127.x.x.x
148
What is the standard port number assigned to Simple Mail Transfer Protocol (SMTP)?
25
149
what is serial transmission
bits are sent one after the other over a single wire from source to destination
150
what is parallel transmission
multiple bits are sent simultaneously over parallel wires from source to destination
151
what is the problem with parallel transmission
can lead to skew if bits travel at different speeds over wires
and arrive at different times
152
when is parallel transmission used (2)
only over short distances
in integrated circuits
153
what are the advantages of serial transmission (4)
more reliable over distances larger than 2m
cheaper
less complexity in connections
less risk of crosstalk
154
what is crosstalk (3)
this is when there is interference between the different cable lines
Electrical signals in one cable generate electromagnetic fields that induce unwanted currents in nearby cables.
can lead to data corruption.
155
Identify two hardware components needed to enable Wi-Fi.
A WAP (wireless Access Point)
Router
156
Explain how the protocol Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) without RTS/CTS works. (3)
Transmitting computer listens to find out if channel is idle (1)
If not idle it waits a random amount of time before trying again (1)
Once the data is successfully sent, the receiving device sends an acknowledgment
157
Explain how a digital signature is produced and verifies that the message has not been tampered with.
Sender creates a hash or digest of message;
The digest is encrypted with the sender’s private key forming the digital signature.
It is bundled with the message; and the bundle is encrypted using the recipient’s public key;
T
he recipient’s private key is used to decrypt the bundle.
158
A digital certificate, explain how this can be used to authenticate the sender of the data.
Issued by a trusted company known as a Certificate Authority (CA)
Verifies the identity of the person who owns public key contained in the certificate, who digitally signed the message
159
Explain how the transport layer of the TCP/IP stack determines which application layer software on the server should deal with a received request.
use the port number to determine which server software should deal with the request
by adding a port number to the request/data/packet;
160
How is the checksum in the footer of the data packet used
Techniques such as checksums are used to check the data by the receiving host
The same checksum is recalculated at the destination
If they do not match, the data has become corrupted and is refused and a new copy is requested to be sent again
161
What are xml and json
Both XML and JSON re data formats used for storing and exchanging information between systems
162
What is meant by client thickness
Refers to the amount of processing and storage the client does compared to the server it is connected to.
163
NEW: Describe the Fetch stage of the fetch execute cycle
Contents of Program Counter transferred to Memory Address Register
Address bus used to transfer this address to main memory
Read signal sent along control bus
Transfer of main memory content uses the data bus
Contents of addressed memory location loaded into the Memory Buffer Register
Increment Program Counter. simultaneously
Contents of MBR copied to CIR
164
NEW: Describe the Decode stage of the fetch decode execute cycle
Control unit decodes instruction held by CIR
Instruction is split into opcode and operand
165
NEW: Describe the execute stage of the fetch decode execute cycle
Opcode identifies type of operation
Operation is performed by control unit, ALU used for calculation
Result may be stored in register or main memory
166
NEW: What is a interrupt and what are the role of interrupts
A signal sent to the processor by hardware of software
So an urgent error condition can be dealt with
167
NEW: What are URLs used for in the RESTful application
Used to carry out a search,
to access a database or resource
168
NEW: Describe the role that will be played by the transport layer of the TCP/IP stack in the transmission of an email from a computer to a email server (3)
169
Why would email servers use well known ports
Communication is initiated by the sender/client
170
