Network Layer

Question 1

What is the main responsibility of the network layer?

Answer 1

Routing. This is the mechanism for exchanging packets between different local area networks and delivering them across multiple intermediate networks to their correct destinations

Question 2

What does each device need per NIC in order to send, receive and route messages?

Answer 2

Each device needs at least one IP address for reach Network Interface Card.

Question 3

What is the original Internet Protocol used for building the Internet?

Answer 3

IPv4, which is still the most widely used protocol

Question 4

How long is an IP address in IPv4?

Answer 4

32 bits long

Question 5

What is “dotted-decimal-notation”?

Answer 5

4 decimal numbers representing 4 bytes separates by dots. This is to make the addresses more human-readable

Question 6

Explain the hierarchical order of IP addresses?

Answer 6

The first two bytes, (ex 130.194) identifies the network. (ex Monash University).
The network is then divided into subnets which are identified by a number of extra bits on the IP address. So an address beginning with 130.194.66.43 will identify a subnet of the Monash Network. The remaining 8 bits identify the host (the device in the subnet)

Question 7

What is a subnet mask?

Answer 7

It tells but how many bits of an IP address are used for the network and how many are used for the subnet mask. So 130.194.66/24 where 24 identifies the number of bits for network and subnet. Then the subnet mask is written as 255.255.255.0 ( 24 1s and 8 0s)

Question 8

In general, how many subnets correspond to how many LANs?

Answer 8

1 subnet to 1 LAN. All the devices inside an LAN typically those connected to the same switch, belonging to the same subnet
1:1

Question 9

When was IPv6 was introduced?

Answer 9

1998

Question 10

What is the difference between IPv4 and IPv6?

Answer 10

IPv6 has the address size from 32 bits to 128 bits. 2^128.

Question 11

What are the three different types of addresses we’ve seen?

Answer 11

• Human-readable addresses (URLs or email addresses)
• IP addresses
• MAC addresses

Question 12

What is the DNS responsible for?

Answer 12

The Domain Name System is responsible for mapping human-readable addresses to IP addresses. it is implemented as an application-layer protocol, where clients send a DNS request to a special DNS server, which would ask the IP address, and the DNS server would send a reply.

Question 13

What is iterative DNS?

Answer 13

A client wants find out the IP address of a domain name,