Lesser Known AWS Features — Day9: AWS Reachability Analyzer: Finding Where Network Traffic Gets Blocked
Day 9 of my AWS learning journey: Exploring Reachability Analyzer and how it helps identify where a VPC network path is being blocked.
Today I explored AWS Reachability Analyzer, and I found it particularly useful for understanding AWS networking.
When an EC2 instance cannot connect to another resource, we usually start checking the route table, security group, NACL, subnet, or gateway one by one. Reachability Analyzer can analyze the configured network path and show whether the destination is reachable. If it isn't, it can identify the component that is blocking the path.
One thing I found interesting is that it doesn't send actual network packets to perform the analysis. Instead, it examines the network configuration and builds a model of the possible path.
For example, if I want to check whether traffic can reach an EC2 instance through a particular network path, I can specify the source, destination, protocol, and other details. AWS then shows the path or explains why it is not reachable.
As someone learning cloud networking, I think this is a really useful tool because it can turn a confusing “Why can't these two resources communicate?” problem into something much easier to investigate.
Have you used Reachability Analyzer while troubleshooting an AWS VPC?
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