Learning series · 6 episodes · Senior / Principal / Staff
The Route Exists. Does the Request Arrive?
Six investigations into private network paths, multi-region topology, BGP outages, anycast session ownership, IPv6 rollout and the WAN latency tax.
Start series →Follow the decisions in order
- Part 1 of 6
Senior
The database is healthy. Why can't the pod reach it?Trace DNS, pod source address, private routes, security policy and the return path without assuming NAT.
- Part 2 of 6
Principal
We connected four regions. Why did one routing change affect all of them?Choose peering, transit gateways and service endpoints from a traffic matrix while limiting failures and privileges.
- Part 3 of 6
Staff
Every server is healthy. Why did the internet lose the route to them?Separate BGP control-plane route withdrawals from healthy application servers, and diagnose internet reachability from outside.
- Part 4 of 6
Staff
The IP address stayed the same. Why did the connection move to another city?Explain shared anycast IPs, routing catchments, and why stateful TCP connections can fail when the chosen site changes.
- Part 5 of 6
Staff
We enabled IPv6. Why did only some customers lose the API?Diagnose failures after adding IPv6 AAAA records, including client fallback variation, NAT64, MTU and policy parity.
- Part 6 of 6
Staff
We upgraded the inter-region link. Why is checkout still taking a second?Quantify the critical path from dependent WAN calls and move work to the data without weakening consistency.