Networking - TCP/IP suite + DNS + others

Question 1

What are the 4 layers of network and describe briefly each layer’s role.

Answer 1

Application, Transport, Internet, Link layers

Application: provide services
Transport: attaching port numbers to transport data from application to application on the computer
Internet: Ensures that data is transmitted to the correct location (computer to computer)
Link: Translation and transmission of data through physics medium (translation of analog waves to digital form)

Question 2

Why are communication protocols necessary?

Answer 2

1. Communication protocols ensures that there is a common rule for the format and structure of the data being transmitted, so that the receiver can handle and unpack the data
2. Communication protocols provide systematic template for network developers to ensure consistency in product standards

Question 3

What is the purpose of TCP/IP suite?

Answer 3

TCP/IP model suite breaks down data transfer over network into layers (ATIL) for efficiency purposes.
Each layer performs a specific function and communicates with the layers above and below it directly, thus this allows for easier updates to individual layers without affecting the whole system.
Each layer is independent and encapsulated from one another, hence this allows for easy identification of bugs and thus problem in the network can be resolved quickly.

Question 4

What is a DNS server?

Answer 4

Domain Name System (DNS) server which translates domain names into IP address which the computer will use to identify the server hosting the website, and sends request to that server’s IP address to load a webpage

Question 5

How does a DNS server work?

Answer 5

1. Client enters URL into search bar
2. Computer checks if domain IP address of the URL is in DNS cache, if not, request sent to DNS resolver
3. DNS resolver sends request to DNS root server
4. DNS root server directs DNS resolver to Top Level Domain (TLD) server, proceeded by 2nd Level domain server and so on until domain IP address of the URL is found
5. The domain IP address of the webpage is returned back to client, where computer will use the domain IP address to communicate with the web server and load the website.

Question 6

How can devices be identified on a network?

Answer 6

IP address and MAC address

Question 7

What is the format of IPv4 addresses?

Answer 7

IPv4 address is 32 bits in length (each number can be from 0-255; thus 8bits per number)
Format:
Four numbers (0-255) separated by dots
255.255.255.255

Question 8

What is the format of IPv6 addresses?

Answer 8

IPv6 addresses is 128 bits in length ( 8 groups of 4 hexadecimal; each hexadecimal takes up 4bits thus 8x4x4=128)
Format: 8 groups of hexadecimal separated by colons
1234:5678:9ABC:DEF0:1234:5678:9ABC:DEF0

Question 9

What is the format of MAC address?

Answer 9

MAC address takes up 48 bits (6 groups of 2 hexadecimal; 6x4x2=48)
Format:
6 groups of 2 hexadecimal
00:1A:2B;3C:4D:5E

Question 10

How does protocols ensure RELIABLE data transfer

Answer 10

1. Protocols are set of established rules to ensure computers can communicate with each other and transfer data between each other.
2. Protocols also includes:
   - rules for error detection and correction such as
   - checksum where hash of the data before and hash of the data after transfered matches to ensure data integrity

Question 11

How does router send data over the network/internet?

Answer 11

1. Data Packets are redirected by the router
2. The router uses a routing table;
3. A routing table has a set of rules which determines which gateway the data is sent to based on the destination and source IP address stored in the packet header

Question 12

What layer does resolving domain name to IP address occur?

Answer 12

Application Layer

Question 13

What layer does port forwarding occur?

Answer 13

Transport Layer

Question 14

What layer does data routing occur?

Answer 14

Internet layer