Question 1

What are the three pillars of observability?

Accepted Answer

**Target Audience:** Beginners who have seen a dashboard or grepped a log file and want to understand what observability means, and candidates who need crisp vocabulary for an interview.
**Difficulty:** Medium
**Verified with:** Node 22.22 and Python 3.12 (both print identical output). The history of the "three pillars" phrase is from CrowdStrike's "Observability (Re)defined" article; the profiles signal status from the OpenTelemetry documentation and ClickHouse's write-up of the Alpha announcem

Question 2

How would you design OpenTelemetry tracing for 200 microservices?

Accepted Answer

**Target Audience:** Engineers who know what a trace is (see the pillars doc) and want to design tracing for a real, polyglot microservice fleet, and candidates preparing for an observability design round.
**Difficulty:** Medium
**Verified with:** Node 22.22 and Python 3.12 (both print identical output). Header format from the W3C Trace Context Recommendation; Collector component behaviour from the loadbalancing exporter README on pkg.go.dev and Grafana Alloy documentation of the tail sampling p

Question 3

What are the trade-offs of microservices vs a monolith?

Accepted Answer

**Target Audience:** Beginners to architecture — you have built a web application; every term is defined the first time it is used.
**Difficulty:** Medium
**Verified with:** Node 22.22 and Python 3.12 (both print identical output). Hop latencies, availabilities and memory sizes are stated assumptions. The case studies are cited to their published coverage (InfoQ, July 2018, on Segment; DevClass, May 2023, on Prime Video), checked October 2026.

> **How to read this doc:** Plain language first, t

SYSTEM DESIGNDECODED.

Medium

What are the three pillars of observability?

How would you design OpenTelemetry tracing for 200 microservices?

What are the trade-offs of microservices vs a monolith?