Cheat sheet & self-check

Pick an answer to see if you got it, and why.

1. Q1. What makes a platform design decision well-founded?

   1. AUsing the most services
   2. BIt starts from requirements and constraints, compares options with trade-offs, and is backed by evidence and a plan for failure
   3. CIt always uses the newest feature
   4. DIt is made quickly
   Show answer

   B. Good decisions are driven by requirements and trade-offs, and they include how the design fails and how that's detected and recovered.

   From lesson 17 · Q&A: platform design, networking & identity

2. Q2. Pods are Pending with 'failed to assign an IP address' while nodes have spare CPU. First fix to evaluate?

   1. ABigger instance types
   2. BCheck subnet free IPs and ENI/IP limits; enable prefix delegation and/or a secondary pod CIDR
   3. CRestart CoreDNS
   4. DAdd a NAT gateway
   Show answer

   B. It's IP exhaustion, either per node (ENI slots) or per subnet. Prefix delegation raises pod density; a secondary CIDR adds address space.

   From lesson 17 · Q&A: platform design, networking & identity

3. Q3. What's the safest general order for an EKS minor-version upgrade?

   1. ANodes, then control plane, then add-ons
   2. BFix deprecated APIs and check insights → control plane → add-ons (compatible versions) → nodes
   3. CAdd-ons first, then everything at once
   4. DOnly the control plane matters
   Show answer

   B. Kubelets may lag the API server within the skew policy, never lead it. Add-ons must be compatible with the new version before nodes move.

   From lesson 18 · Q&A: operations, security, cost & reliability

4. Q4. An executive asks for 'five nines' on the platform. What's the architect's first response?

   1. AAgree
   2. BClarify which user journeys need it, what it costs (multi-region, active-active data), and agree SLOs per tier
   3. CRefuse
   4. DBuy bigger instances
   Show answer

   B. Availability targets drive architecture and cost dramatically. Set SLOs per service tier based on business impact.

   From lesson 18 · Q&A: operations, security, cost & reliability