VPC Router

• Each VPC has an implicit router that manages how network traffic is directed.

• The route tables control how traffic moves between subnets, the internet, and other AWS resources.

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⚙️ Key Features

• Route Tables:

  • Each subnet in the VPC must be associated with a route table that defines how traffic is routed.

  • You can either use the default (main) route table or create custom route tables for specific subnets.

• Associating Subnets:

  • A subnet can only be associated with one route table at a time, but you can associate multiple subnets with the same route table.

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🧠 Quick Summary

Feature	Description
VPC Router	Implicit router manages traffic for the VPC
Route Tables	Control traffic direction for subnets
Subnet Associations	One route table per subnet, but multiple subnets can share
Default Route Table	Subnets not explicitly associated are linked to the main route table

• Every VPC has an implicit router that uses route tables to control traffic flow.

• Route tables determine where network traffic is directed within the VPC and beyond.

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🧭 Route Tables and Subnets

• Every subnet must be associated with one route table.

• You can:

  • Explicitly associate a subnet with a route table.

  • Or let it use the main route table by default.

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📌 Important Rules

• One subnet → One route table (only one at a time).

• One route table → Multiple subnets (many subnets can share a route table).

• The main route table is automatically created with the VPC and used by default.

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🧠 Quick Summary

Feature	Description
Implicit Router	Exists in every VPC, uses route tables for traffic direction
Subnet Association	Each subnet must be linked to one route table
Default Route Table	If none is specified, subnet uses the main route table
Sharing Route Tables	Multiple subnets can share one route table