Networks - IP Domain DNS MAC

Question 1

How does IPv4 work?

Answer 1

Each device has a unique 32 bit binary number address.

0101 1001 1001 0001 0100 1101 0110 0110

This sequence is broken into 8-digit chunks called octets. Each octet is changed into denary, separated by dots.

89.145.77.102

Question 2

What does an IP address contain?

Answer 2

The address of the network.

• Uniquely identify networks
• Send messages between different networks

The address of the node within the network
- Send messages to specific computers within a network

Question 3

What does IP classes solve?

Answer 3

Not enough room for either node address or network address within the 32 bits given.

Question 4

What is IP Class A for?

Answer 4

Very large networks

- 16 million nodes

Question 5

What is IP Class B for?

Answer 5

Medium sized networks

- 64,000 nodes

Question 6

What is IP Class C for?

Answer 6

Small networks

- 256 nodes

Question 7

What is a static IP address?

Answer 7

An IP address that doesn’t change.

Question 8

What is a dynamic IP address for?

Answer 8

Temporary use while a device is connected. As soon as the device disconnects, that IP becomes available for other devices to use.

Question 9

How many addresses is IPv4 capable of?

Answer 9

4 billion

Question 10

Why was IPv6 introduced?

Answer 10

There are more internet capable devices online than there are available IPv4 addresses.

Question 11

How many bits does IPv6 have?

Answer 11

128 bits

Question 12

Why hasn’t the introduction of IPv6 made any difference to the way the internet runs?

Answer 12

Both IPv6 and IPv4 can coexist.

Question 13

Why was Domain Name System developed?

Answer 13

IP addresses are not convenient to remember.

Question 14

What is DNS?

Answer 14

A system that assigns names to IP addresses that use the full set of alphanumeric characters.

Question 15

How are domains organised and allocated?

Answer 15

By IANA and its member registrars (just like IP numbers)

Question 16

What are the two parts of a domain?

Answer 16

A descriptive string of characters
EG: brainscape
A suffix describing which Top Level Domain it belongs to
EG: .com

Question 17

How are domain names registered and handled?

Answer 17

By the Domain Name System

Question 18

When you enter a URL, how is the IP address of that website retrieved?

Answer 18

An online DNS server receives the domain name request from the browser, and finds the related IP address in a database. It returns that info back.

Question 19

Why must the DNS be extremely robust and trustworthy?

Answer 19

It has to serve millions of browser requests all of the time.

Question 20

How does the DNS achieve being extremely robust and trustworthy?

Answer 20

There is a network of hundreds of DNS root servers around the world.

Question 21

What do the root DNS servers contain?

Is there anything they do?

Answer 21

Backups of the entire IP database. Some have the authority to hand out domains for specific TLDs

Question 22

How do the root DNS servers stay up to date?

Answer 22

They check with each other.

Question 23

Why must root DNS servers keep up to date?

Answer 23

Domain names are being bought and sold constantly.

Question 24

What happens if someone enters a domain name into their browser that the DNS doesn’t recognise?

Answer 24

An error code is sent back to the web browser.

“Website cannot be found” displayed.

Question 25

What is a MAC address useful for? Why?

Answer 25

MAC is useful for network diagnostics because it never changes, so it can identify individual devices.

Question 26

How is a MAC address formatted and displayed as?

Answer 26

A set of six hexadecimal numbers separated by hyphens.

Question 27

How does MAC filtering work?

Answer 27

Networks can be configured to only accept connections from devices with a MAC address from an approved list.

Question 28

What benefit does MAC filtering have?

Answer 28

It prevents unknown devices from getting into the network.