Design Lab — Match the mechanism to the RTO and the RPO
AZ-305 › Unit 3 › Design solutions for backup and disaster recovery
Design Lab — Match the mechanism to the RTO and the RPO
Lab brief
- 3 — Business continuity
- 15–20%
- 20 minutes
- $0 — no subscription needed
- Foundational
Every business-continuity question on this exam is the same question wearing different clothes: a workload states an RTO and an RPO, and exactly one mechanism meets both at the lowest cost. Candidates lose marks by reaching for the most powerful option instead of the cheapest sufficient one, and by confusing three things that are not interchangeable — backup, high availability, and disaster recovery.
This lab is a decision drill, not a walkthrough. Read the brief, commit to your answers before you reveal anything, then check them. Guessing and peeking teaches nothing; the value is entirely in the commitment.
The brief
Litware Insurance — continuity review
Customer-facing claims intake, running on Azure App Service in West Europe. Must keep serving if a single availability zone is lost. RTO 15 minutes, RPO near zero. Revenue-bearing: every hour offline is quantifiable loss.
Commit before you reveal
Write your four answers down — on paper, in a note, anywhere but in your head — then open each card.
▶Why this matters more than it looks — open only after you have written your answers
Retrieval is the mechanism that moves knowledge into recall. Reading an explanation you have not first committed against feels productive and produces almost nothing; the effort of retrieving a wrong answer is what makes the correction stick. In the exam you will not have a reveal button, so practising the reveal habit is practising the wrong skill.
Question 1 — the cheapest sufficient mechanism
The Tier 3 reporting VM needs RTO 8 hours and RPO 24 hours, and full rebuild automation already exists. Which recommendation meets the requirement at the lowest cost?
Question 2 — the storage redundancy trap
The Tier 2 document archive must survive the loss of the primary region AND stay READABLE during that outage. Which statements are true and relevant to this choice? Select all that apply.
Select all that apply
Question 3 — who is allowed to press the button
For the Tier 1 claims database — RTO 15 minutes, and the team wants to rehearse failover on a schedule — which failover policy should the failover group use?
Question 4 — the order that keeps you honest
Put the business-continuity design method into the order that prevents over-engineering.
Put the steps in order
- 1Choose the cheapest mechanism that satisfies both numbers
- 2Classify the workload tier and its business impact
- 3Rehearse the failover and record the evidence
- 4State the required RTO and RPO as numbers
Why the runner-up loses
Three mechanisms that are not interchangeable
| Attribute | Recommended | ||
|---|---|---|---|
| Answers the question | Can I go back to a previous point in time? | Can I survive losing a component or a zone? | Can I survive losing the region? |
| Typical Litware fit | Tier 3 reporting VM, RPO 24h | Tier 1 claims API, zone redundancy | Tier 1 claims database, failover group |
| What it does NOT protect against | An outage — restore takes time you may not have | Regional loss, and data corruption replicated to every zone | Corruption or deletion, which replicates to the secondary too |
| Cost shape | Storage of recovery points only | Redundant capacity in the same region | A second region's capacity, continuously |
The row that decides most exam questions is the third one. Every mechanism replicates its own blind spot: high availability faithfully copies corrupted data across zones, disaster recovery faithfully copies it to the secondary region, and only a backup holds a point in time before the corruption. This is why a design that names only one of the three is almost always incomplete.
The shape of the answer
The traps that catch people
The method, for any question of this shape
How to attack a BCDR question in 90 seconds
Extract the two numbers
Find the RTO and the RPO before reading the options. If the question does not state them, find the phrase that implies them — 'nightly refresh' is an RPO of 24 hours, 'revenue-bearing' is not a number but tells you the tier.
Before you move on
You have met the pattern once. The value comes from the second and third encounter, so revisit this lab after the Unit 3 lessons and answer the four cards again from a cold start — if you can reconstruct why the runner-up loses, rather than only which option is right, the pattern has transferred.