9.3 The Internet

Question 1

what is The internet?

Answer 1

A network of interconnected computer networks which uses an end-to-end communication protocol.

Question 2

How is the internet connected?

Answer 2

It is mostly a wired network with cables that pass under oceans to connect the different continents.

Question 3

What is an internet service provider (ISP)

Answer 3

A company that provides its customers with access to the internet.

Question 4

What is a packet in terms of the internet?

Answer 4

A container in which data is transmitted over networks. They’re labelled with addresses for the sender and the recipient and contain information intended for the recipient.

Question 5

What is the role of packet switching and routers?

Answer 5

One message is frequently split into multiple packets, each of which is sent to its
recipient via the best possible route. Packets are reassembled with other packets that form part of the same message by their recipient. Packets usually have to pass through number of routers before reaching their destination. Packets’ recipient addresses are used by routers to determine where to send them. Every time that a packet passes through a router, a hop is said to occur. A packet’s time to live (or TTL) is a number that indicates how many hops the
packet can partake in and is reduced by one with each hop. When a packet’s TTL expires, the packet is dropped. The recipient will notice a missing packet and request that the sender transmits the missing packet again

Question 6

Explain what a packets time to live (TTL is)?

Answer 6

Holds the number of hops a packet can go through before
being dropped

Question 7

What are the primary components of a packet?

Answer 7

Sender’s address, receiver’s address, packet contents, time to live (TTL), sequence number

Question 8

Explain the purpose of a packet’s sender’s address?

Answer 8

Identifies where the packet was sent from, and therefore where the response should be sent to.

Question 9

Explain the purpose of a packet’s receiver’s address?

Answer 9

Identifies the packet’s intended recipient, allowing it to be routed to the correct device.

Question 10

Explain the purpose of a packet’s contents?

Answer 10

Where the packet holds the data that is being transferred

Question 11

Explain the purpose of a packet’s sequence number?

Answer 11

Contains the number of packets in a message and identifies a packet’s position in relation to others.

Question 12

What do routers and gateways do together?

Answer 12

They connect different networks, allowing packets to reach their destination.

Question 13

Explain what a router does?

Answer 13

Send packets to their recipient via the fastest possible route. They hold tables with information relating to the fastest routes to certain devices.

Question 14

Explain what a gateway does?

Answer 14

As two networks could use different protocols, packets must be modified so they conform to both protocols. Gateways strip away most of the packet’s details, leaving just the packet’s contents. The gateway will then give packets new sender and receiver addresses which comply to the new protocol.

Question 15

What is a uniform resource locator (URL)?

Answer 15

An address assigned to files on the internet. Different protocols can be used in URL’s to access different types of files in different ways.

Question 16

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “https://”?

Answer 16

It is the protocol being used to access the file.

Question 17

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “www”?

Answer 17

It is the subdomain for world wide web.

Question 18

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “bbc.co.uk”?

Answer 18

It is the domain.

Question 19

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “/news”?

Answer 19

It is the directory of the file being requested.

Question 20

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “/technology”?

Answer 20

It is the subdirectory of the file being requested.

Question 21

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “/index”?

Answer 21

It is the name of the file being requested.

Question 22

In the URL (https://ww.bbc.co.uk/news/technology/index.html) explain the purpose of “.html”?

Answer 22

It is the file’s extension.

Question 23

What is the purpose of a domain name?

Answer 23

Identifies an organisation or individual on the internet. They use alphanumeric characters which make them easy for humans to remember.

Question 24

what is a fully qualified domain name (FQDN)?

Answer 24

A domain that specifies an exact resource and can be interpreted in only one way. An FQDN will always include the servers host name. For example “www”.

Question 25

What uses an internet protocol (IP) address?

Answer 25

Every computer on the internet and every device that communicates on a network.

Question 26

Explain the purpose of domain names?

Answer 26

As IP addresses are not easy for humans to remember, domain names are used. They map to IP addresses, meaning they are a human-friendly representation of an IP address.

Question 27

Explain the functionality of a domain name server (DNS)?

Answer 27

A domain name server is used to translate domain names into their corresponding IP address. It stores a table of domain names and their corresponding IP address

Question 28

What is the role of an internet registry?

Answer 28

To protect the world's depleting pool of unallocated IP addresses. When a new IP address is requested an Internet registry will first look for a previously allocated IP address that has become unused rather than allocate a brand new IP address straight away.

Question 29

What does a firewall do?

Answer 29

Sits between a device and the internet and regulates the packets that pass through it. Firewalls can be software or hardware and work as a proxy server which can perform both packet filtering and stateful inspection.

Question 30

How does packet filtering work and what does it do?

Answer 30

Firewalls use packet filtering to accept and block packets based on their source IP address or the protocol that they are using. A network's administrator can specify particular IP addresses or protocols to block or use automatic filtering software that can block suspicious packets.

Question 31

What is stateful inspection and how does it work?

Answer 31

Stateful inspection actually examine the content of a packet before deciding whether to allow it through the firewall. Some firewalls keep a record of current in a network, allowing them time to filter out packets that aren't related to activity on the network.

Question 32

What is a proxy server and what do they do?

Answer 32

A server that sits between a public network and a private network. They manage every packet that passes between the two networks. Firewalls can be said to act as proxy servers when they control the movement of packets between public and private networks.

Question 33

How do firewalls provide anonymity?

Answer 33

When a device in a private network sends a packet through a firewall and into a public network, the packet's "sender" address is that of the firewall, rather than the devices private IP address. Provides anonymity to devices on privates networks as their private address is never sent beyond the private network.

Question 34

How does symmetric encryption work?

Answer 34

Both the sender and receiver share the same private key. The key is used to both encrypt and decrypt data sent between the two parties. Before sending any information the sender and receiver must participate in a key exchange to ensure that they both have a copy of their shared key.

Question 35

What is the disadvantage of symmetric encryption.

Answer 35

If the key exchanged over a network, it is vulnerable to interception.

Question 36

How does asymmetric encryption work?

Answer 36

Each device has a pair of mathematically related keys. One key is kept private (private key) and the other is shared on the internet (public key). When a message is encrypted with a public key, only the corresponding private key can decrypt it and vice-versa. Before a message is sent it is encrypted by the sender using the recipient's public key. The message can only be decrypted by the corresponding private key, the recipient's private key. Only the recipient has access to this key so the recipient is the only person who can decrypt the message.

Question 37

when are digital signatures used?

Answer 37

When using asymmetric encryption, it can be used to verify the sender of a message and to verify that a message has not been tampered with during transmission.

Question 38

What are the 4 stages of digital signature encryption?

Answer 38

1) digest of the message is created 2) the digest is encrypted with the sender's key 3) The encrypted with the sender's private key 4) The message and appended digest are encrypted with the recipient's public key

Question 39

How does digital signature decryption work?

Answer 39

When the recipient receives the message, they: ○ decrypt the message using their private key ○ decrypt the digest using the sender’s public key ○ carry out the same digest algorithm on the message ○ check whether their result matches the now decrypted digest

Question 40

What is a digital certificate and how does it work?

Answer 40

It verifies ownership of a key pair used in asymmetric encryption and can be used to check that a fake key pair isn't being used by an imposter.

Question 41

What do digital certificates contain?

Answer 41

They contain: a serial number, the owner's name, an expiry date, the owner's public key and the certificate authority's digital signature.

Question 42

Name the 3 types of malware

Answer 42

worms, trojans and viruses

Question 43

What are worms in computing?

Answer 43

Pieces of malicious software that can self-replicate between computers, either within a network or by users downloading and running a malicious file.

Question 44

What are Trojans in computing?

Answer 44

A type of malware that is disguised as a benign file that users can be tricked into opening. Often spread as email attachments or downloaded from malicious websites.

Question 45

What are features of viruses in computing?

Answer 45

Require a host file in which to reside These files are typically executable files Can lie dormant in a computer until their host file is opened or run Can spread between computers over a private network , the Internet or even through the use of physical media

Question 46

What are some ways to prevent malware?

Answer 46

Good code quality, antivirus software, up-to-date software, employee training.

Question 47

Why can good code quality prevent malware?

Answer 47

Malware often exploit bugs in code that enable them to take hold of a computer system.

Question 48

How can installing antivirus software prevent malware?

Answer 48

They are specialist pieces of software that scan files on a computer and remove any suspicious files.

Question 49

How can training employees prevent malware?

Answer 49

They can be trained about the risks of opening suspicious email attachment or other methods in order to reduce the risks posed by malware.