Route Tables

• Route tables act as router.
• By default we will a have default route table.
• Subnets can be associated with route table, if not associated then default route table will be used for routing
• When we are using any ranges in security groups or NACL or Route tables restrictions can be applied on basis of network id
  • Specific Ranges
  • Any Ip Address
  • Specific IP Address

# Specific Range
10.0.0.0/16 => 10.0.x.x
# Any IP
0.0.0.0/0 => x.x.x.x
# Specific IP
100.100.100.100/32

• Default Routes in Route table: All the communication within vpc is routable
  
• Connection to Internet gateway
• Lets add a route to forward packets to internet gateway
  
• For demonstrations refer classroom

Lets create public and private subnets

• Your application has three layers
  • web
  • app
  • db
• Only web should be exposed to internet
• We have six subnets
  • web1
  • web2
  • app1
  • app2
  • db1
  • db2
• We have create the internet gateways
• Lets create two route tables
  • public: will be associated with subnets web1, web2 and will have route to internet gateway
  • private: will be associated with other subnets and will not have route to internet gateway
    
• web1, web2 are public subnets as they have route to internet
• app1, app2, db1, db2 are private subnets as they dont have route to internet
  
• Exercise:
  • Create a vpc with 4 subnets
    • web
    • app
    • mgmt
    • db
  • Only mgmt subnet should be public, rest of the subnets should be private
  • Create an ec2 instance in mgmt and web
  • Try to connect to ec2 in web from your system and check if it is getting internet or not