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Route tables

  • What it is
    • A set of rules (routes) that decide where network traffic from a subnet is directed, matched by destination CIDR.
  • How it works
    • Each route = destination (CIDR) → target (a gateway, NAT, peering connection, endpoint, etc.).
    • Longest-prefix match wins; the local route for the VPC’s own CIDR is always present and can’t be removed.
    • Every subnet is associated with exactly one route table (the VPC’s main route table by default).
  • This is what defines public vs private
  • Common targets
  • Not to be confused with
    • security groups / network ACLs — those filter (allow/deny) traffic. Route tables direct it. Both must permit a packet for it to flow.

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