The Internet [1]

Question 1

What is a URL?

Answer 1

A character string that refers to the location of an internet resource.

Question 2

What is a Fully Qualified Domain Name?

Answer 2

The complete domain name for a specific computer, or host, on the internet. It consists of the hostname and the domain name.

Question 3

How does a Domain Name Server work?

Answer 3

• The DNS stores a database of FQDNs and corresponding IP addresses.
• DNS servers are organised into a hierarchy
• If one DNS server cannot resolve a lookup, the query will be passed to another DNS server.

Question 4

Why would a DNS not be required?

Answer 4

• The local computer already has a copy of the needed IP address in a hosts file
• The local computer has a cache of recent DNS queries.
• The URL typed in already contains an IP address
• The URL refers to a local resource.

Question 5

What is an Internet Protocol Address?

Answer 5

A unique string of characters that identifies each computer using the Internet Protocol to communicate over a network.

Question 6

What is a NAT table?

Answer 6

A NAT table is used to match the private IP addresses with Public IP addresses.

Question 7

What are the advantages of using a NAT table?

Answer 7

• A unique address isn’t needed for every single device
• Improves security as the private IP addresses aren’t being broadcast over the Internet.

Question 8

What is Port Forwarding?

Answer 8

Technique used when a client needs to communicate with a server connected to a private network.

Question 9

How does Port Forwarding work?

Answer 9

• Client sends packets to the public IP address of the router belonging to the server’s private network.
• Packets sent by client contain the port number of the application that the client wants to access
• Private network’s router forwards the packets to the server using NAT.

Question 10

What is a Socket?

Answer 10

A socket is an end point of communication flow across a network. They are made up of an IP address and a port number. (e.g 192.168.3.205:80)

Question 11

What is a Port?

Answer 11

Ports are used to identify a particular process or application on a network.

Question 12

What is Port Scanning?

Answer 12

A technique hackers use where they look for open ports and message ports to see if they are being used. If they aren’t being used, the hacker can get in

Question 13

What is the Dynamic Host Configuration Protocol (DHCP)?

Answer 13

A device that is responsible for assigning a Dynamic IP address.

Question 14

What are the advantages of DHCP?

Answer 14

• Facilitates efficient use of a limited pool of IP addresses
• Avoids errors, e.g. duplicating IP addresses.

Question 15

What is the Regional Internet Registry?

Answer 15

An organisation that manages and controls Internet addresses in a specific region - usually in a country or a continent

Question 16

What does the RIR do?

Answer 16

They are responsible for allocating and assigning IP numbers to devices, websites, information systems, autonomous systems, etc.

Question 17

What is a Router?

Answer 17

A device that interconnects with two or more computer network that interchange packets with each other

Question 18

What is Packet Switching?

Answer 18

A method for sending data where the data is divided into packets.

Question 19

What kind of information do Packets contain?

Answer 19

• Sender’s address
• Receiver’s address
• Packet contents
• Time to live (TTL)
• Sequence number

Question 20

How does Packet Switching work?

Answer 20

1. Messages are split into packets.
2. The destination address is added to each packet
3. Packets are given a sequence number
4. Each packet is dispatched to the internet through a router
5. Packets are sent independently
6. Receiver re-orders packets into correct sequence
7. Protocol bits are stripped from the packets so that the original data can be passed to the application needing it

Question 21

Advantages of Packet Switching

Answer 21

• Makes very efficient of the network, with no tied up lines
• Can easily get around broken bits of the network by detecting the failure and resending the packets that didn’t make it.

Question 22

Disadvantages of Packet Switching

Answer 22

• Not good for small data packets
• Can suffer from latency

Question 23

How are packets routed across the Internet?

Answer 23

• Routers use a hierarchical organisation of routers that the packet will travel across
• The path that the packet takes is selected by each router and isn’t determined at the start
• The route may change as a result of congestion
• The route is determined by using the network ID of the destination IP address.

Question 24

How does a Thin Client work?

Answer 24

• All / most processing is done by a central server
• User inputs are transmitted from a workstation to the server over a network
• Applications aren’t installed on thin client workstations.
• Operating system is loaded by clients from the server at boot.

Question 25

What are the Hardware requirements of a Thin Client?

Answer 25

• Workstations can have a slower processor, reduced RAM or even no HDD
• Higher bandwidth network connection is required

Question 26

What is The Internet?

Answer 26

A global network of interconnected computer networks that use the Internet Protocol (IP)

Question 27

What is an Intranet?

Answer 27

A private computer network available to a closed community that uses IPs to share part of an organisation’s information with its members.