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Name Route Table ID by "Elplicit subnet association" and "Main" like below:

STEP

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1) Usually automatically generated, and requires renaming like "Public RT" for you

2) Select your route table →  move tap to "Routes" →  add route → add "0.0.0.0/0" and set target to internet gateway defined at STEP 3

3) move tap to "Subnet Associations" →  Edit subnet associations -> Select only "public subnets" -> Save

STEP 7. Set Private Route Tables

1) Create Private Route Table and name it like "Private RT" for you

2) move tap to "Subnet Associations" →  Edit subnet associations →  Select only "private subnets" defined at STEP 5 →  Save

STEP 8. Create security group

1) One default inbound rule will be listed

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