AWS Classroom Series – 27/Oct/2020

What is ip address, subnet mask and default gateway

• To uniquely identify a system in a network every system is given an unique address which is referred as IP address
• Execute ipconfig (ifconfig) from terminal
• From the above image we can understand ip address which is unique id given to the system in a network for communication
• Basic Network Rules
  • A system (laptop/mobile) can communicate with any other system (laptop/mobile) in the same network
• Two Questions to be answered
  • How does system know that other system is from same network?
  • Google.com is not in my home network then how is it working?

How does system know that other system is from same network?

• IP Address: Ip address is combination of network id and host id
• The ipaddress in the above example was 192.168.0.198 What is network id in this & What is host id in this?
• Just by looking at ip we will not be able to tell network id and host id, we need subnet mask for that
• Lets try the below sample.

ip: 192.168.0.198
sm: 255.255.255.0
------------------
    192.168.0 (255) => Network Id
    198(0) => Host id


ip : 10.10.10.18
sm : 255.255.0.0
-----------------
    10.10 (255) => Network Id
    10.18 (0)   => Host id

• System will come to know if the other system is in same network if it has same network id
• Little bit more ip:
  • The ip we have used is reffered as IPv4 which is a 32 bit number. Ip’s are represented as x.x.x.x where x => 8 bit number. x has minimum value of 0 and maximum value of 255

Google.com is not in my home network then how is it working?

• Lets ping google
• In networking based on rule two systems can communicate only if they are in same network.
• There is a networking component called as router. The responsibility of router is to forward packets from one network to other.
• Generally router ip address is stored as Default Gateway
• Your router forwards the packet to other network which forwards to other this happens till google.com is reached (hopping).

What are components of my home internet connection & its relavance

• Router: Router is used forward packets to the internet
• Modem: connects to the internet service providers network
• What happens if modem is down?
  • Will we have network? Yes we will have network without internet access
• What will happen if router is down?
  • We will have no network (Network will be down)

Exercise:

1. Create AWS Account Refer Here
2. Create one ec2 instance and delete it Refer Here
3. Install necessary Softwares Refer Here