Connect two private neighborhoods — VPC and VPC peering

Your goal

Plan a direct private connection between two separate VPC networks.

Why this matters

Two teams need their apps to communicate privately. You will check address ranges, add routes in both directions, and understand why this link does not connect every other network.

Words you will use

A CIDR range is a block of network addresses. Peering links two VPCs. A route tells traffic where to go. Transitive routing means reaching a third network through an intermediate one.

How to proceed

Read each situation and choose an answer. The lesson explains the result. Try again if needed, then continue through all three decisions and finish the tour.

1. Check the addresses first

Both VPCs currently use the same private address range. A destination address could refer to a machine in either network. Choose the first design correction.

What must the two networks have?

Non-overlapping address ranges.

VPC peering requires non-overlapping address ranges. Plan addresses before connecting networks. Renaming a VPC does not change its addresses or solve ambiguous destinations.

The two networks have distinct address space.

VPC A addresses ≠ overlapping VPC B addresses

2. Add the return path

The peering connection is accepted, but app requests still fail. Traffic needs a route to the other network and a way back. Choose the next work.

What else is required?

Appropriate routes on both sides and traffic permissions.

An accepted peering connection does not automatically rewrite every route or security rule. Add the needed routes in both VPCs and permit the intended traffic, then test a full request and response.

The request and reply both have a permitted path.

A route → peer → B; B return route → peer → A

3. Avoid an invisible third link

VPC A peers with B, and B peers with C. The team assumes A can use B to reach C. Choose the correct explanation.

Does that path exist automatically?

No; VPC peering is not transitive.

A peering connection is a direct relationship between two VPCs. It does not let one VPC route through its peer to a third. Design the additional connectivity explicitly for the network you need.

The diagram shows only connections that actually exist.

A ↔ B and B ↔ C does not create A ↔ C

Practice, then check your understanding

In the interactive tour, make each decision before seeing the outcome. Wrong answers receive coaching, and replay gives you a fresh attempt without duplicating earned XP.

Read the official AWS documentation for service behavior and production details.