What is subnet mask and default Gateway

• Screen shot

• Networking core concepts

  • Two systems which are in same network can communicate with each other
  • Router can help in transferring network packets from one network to other

• Two Systems connected in same network can communicate with each other

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  • But how does system A know that System B in same network?
    • Ip Address => Network id + host
    • Lets look at some samples

Identifying network id and host id

• Just by ip address we can make out what is network id and what is host id. We need subnet mask for that
• Example 1:

ip:  192.168.100.102
sm:  255.255.255.0
nid: 192.168.100
hid: 102

• Example 2:

ip: 10.10.4.5
sm: 255.255.0.0
nid: 10.10
hid: 4.5

• Two machines will know they can communicate with each other if they have same network id

Need for default gateway

• Typical home network connection
• Ping from home to google works because of default gateway (Wifi Router) forwards the packet to next connected network

Creating Network

• Networks are of two types
  • Public Network:
    • Any one from internet can access your network
  • Private Network
    • This network will be private
    • This network can connect to internet
• In Azure We create private networks. Exposing your servers to public internet will be handled by Azure, you have to just inform.
• When we create a network => we need to specify the range of ip addrresses available for the network. This range is often chosed depending on number of systems to be connected to network.

Scenario 1:

• QT has on office where there are
  • Dev Workplace: This needs 250 connections
  • Lab Workplace: This needs 250 connections
• We are asked to create a private network for this

Scenario 2:

• QT has an office building with 4 floors. Each floor has two work areas capable of connecting 250 devices
• We are asked to create private network for this