AWS NWD4: Route Table
A Route Table in Amazon Virtual Private Cloud is a set of rules that determines where network traffic should be directed inside a VPC. It acts like a navigation map that tells AWS which path a packet should follow to reach its destination.
Every route table contains routes, and each route has two main parts:
Destination: The IP range where traffic is going
Target: The resource that should receive the traffic
Why Route Tables Are Important
Route tables are responsible for controlling the flow of network traffic between:
Subnets
The internet
Other VPCs
On-premise networks
Without route tables, AWS resources inside a VPC would not know how to reach other networks.
Example Route Table
| Destination | Target | Meaning |
|---|---|---|
| 10.0.0.0/16 | local | Internal VPC communication |
| 0.0.0.0/0 | Internet Gateway | Send internet traffic outside |
Explanation:
localmeans traffic stays inside the VPC0.0.0.0/0means all internet traffic
Types of Route Tables
Main Route Table
Every VPC automatically has a main route table.
Subnets use this table unless another route table is explicitly associated with them.
Custom Route Table
You can create additional route tables and attach them to specific subnets to control traffic differently.
How Route Tables Work
When a packet enters a VPC:
AWS checks the destination IP address
The VPC router looks at the subnet's route table
It matches the destination with the correct route
The packet is forwarded to the target resource
Common Route Targets
Route tables can send traffic to:
Internet Gateway (internet access)
NAT Gateway (internet access for private subnets)
VPC Peering connections
VPN gateways
Transit gateways
Local VPC network
The route table decides which subnet or gateway should receive the packet next.
Key Points for Interviews and AWS Exams
Route tables control traffic routing inside a VPC
Each subnet must be associated with one route table
A route consists of destination and target
The main route table is used by default
Custom route tables allow fine-grained traffic control
One Line Definition
A route table is a set of routing rules that determines how network traffic flows within and outside a VPC.