4.9.3 The Internet

Question 1

What is the relationship between the domain name and IP address?

Answer 1

Each domain name has a direct relationship with an IP address.

Question 2

What happens when you enter a domain name into your browser?

Answer 2

Domain name server is used to translate the domain name into its corresponding IP address.

Question 3

What does the domain name server hold?

Answer 3

Table of domain names and their corresponding IP address.

Question 4

What happens if the DNS does not have a record for the domain being accessed?

Answer 4

• The request will be passed to another DNS.

Question 5

What occurs with rarely visited websites?

Answer 5

Will require numerous changes of servers before a record can be found, making those websites slightly slower to access than large websites

Question 6

What is the internet registry?

Answer 6

The internet registry is an organisation responsible for the allocation of IP addresses.

Question 7

How many internet registries are there?

Answer 7

Five, each operating in a different geographical area.

Question 8

What is the purpose of a registry?

Answer 8

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 9

What is a firewall?

Answer 9

• Firewall sits between a device and the internet and regulates the packets that pass through it.

Question 10

What are the two kinds of firewall?

Answer 10

Hardware

Software

Question 11

How does a firewall work as a proxy server?

Answer 11

A firewall can work as a proxy server which can perform both packet filtering and stateful inspection.

Question 12

How do firewalls use packet filtering?

Answer 12

• Firewalls use packet filtering to accept and block packets based on their source IP address or the protocol that they are using ( determined by their port number ).
• A networks administrator can specify particular IP addresses or protocols to block or use automatic filtering software that can block suspicious packets.

Question 13

How does stateful inspection work?

Answer 13

• Stateful inspection examines the contents of a packet before deciding whether to allow it through the firewall.
• Some firewalls keep a record of current connections on a network allowing them to filter out packets that aren’t related to the activity on the network.

Question 14

What is a proxy server?

Answer 14

A server that sits between a public network and a private network.

Question 15

What is the purpose of a proxy server?

Answer 15

• Devices that manage every packet that passes between the two networks.

Question 16

Why are firewalls proxy servers?

Answer 16

They control the movement of packets between public and private networks

Question 17

What happens when a device in a private network sends a packet through a firewall into a public network?

Answer 17

• The packet senders address is that of the firewall rather than the device’s private IP address.
• This provides some degree of anonymity to devices on private networks as their private address is never sent beyond the private network.

Question 18

Why is anonymity provided via firewalls?

Answer 18

Private address is never sent beyond the private network.

Question 19

When is encryption used?

Answer 19

When information needs to be transmitted securely over a network, encryption is used.

Question 20

What is encryption?

Answer 20

The process of scrambling data so that it cannot be understood if intercepted.