The AZ-305 (Designing Azure Infrastructure Solutions) is Microsoft's expert-level Azure certification. It sits at the top of the Azure architecture path — and it shows. This is not a service knowledge test. It's a design judgment test.
If you've passed AZ-104 and you're preparing for AZ-305, you already know Azure well enough. The question is whether you can apply that knowledge to architect solutions under constraints — cost, compliance, resilience, scale — the way a real solutions architect would.
That's what this guide is about.
Prerequisites — do you need AZ-104 first?
Officially, Microsoft recommends AZ-104 before AZ-305. In practice, it's more than a recommendation — AZ-305 assumes you know how to configure the services it asks you to design with. You won't be asked how to configure a VNet, but you will be asked to design a network topology across multiple regions with specific latency, security, and cost requirements.
If you haven't done AZ-104, read the AZ-104 Study Guide first. If you have, you're ready to move up.
What AZ-305 actually tests
The exam covers four design domains:
| Domain | Exam weight |
|---|---|
| Design Identity, Governance & Monitoring Solutions | 25–30% |
| Design Data Storage Solutions | 15–20% |
| Design Business Continuity Solutions | 15–20% |
| Design Infrastructure Solutions | 30–35% |
Infrastructure Solutions is the largest domain — networking, compute, application architecture, and migration. Identity & Governance is close behind and is where most candidates lose unexpected marks.
The exam is 40–60 questions, 120 minutes, $165. Case studies appear — multi-page scenarios where you answer several questions based on a single detailed business and technical brief.
The three hardest areas on AZ-305
1. Identity and governance — Azure AD, RBAC, and policy at scale
AZ-305 goes deeper than AZ-104 on identity. You need to design solutions for:
- Multi-tenant Azure AD scenarios
- Privileged Identity Management (PIM) for just-in-time access
- Azure AD B2B and B2C for external identities
- Management group hierarchies with policy inheritance
- Azure Policy and blueprint assignments for compliance at scale
The exam asks you to design the least privilege architecture — not just assign a role, but choose the right scope, the right role, and the right enforcement mechanism across a complex org structure.
2. Business continuity — RTO, RPO, and the right service for each scenario
Every business continuity question on AZ-305 hinges on two numbers: RTO (Recovery Time Objective — how fast you need to recover) and RPO (Recovery Point Objective — how much data loss is acceptable).
You need to know exactly which combination of services meets which RTO/RPO targets:
- Azure Backup — simple backup, higher RTO
- Azure Site Recovery — VM replication, low RTO for IaaS
- Active geo-replication (SQL Database) — near-zero RPO for databases
- Availability Zones vs Region Pairs — when to use each for HA vs DR
The mistake candidates make: they know what each service does but can't quickly map a given RTO/RPO requirement to the right architecture.
3. Infrastructure design — networking at scale
AZ-305 network questions are more complex than AZ-104. You'll design:
- Hub-spoke topologies with Azure Firewall and VPN/ExpressRoute
- Private endpoints vs service endpoints (and when each is appropriate)
- Azure Front Door vs Application Gateway vs Traffic Manager — for different traffic patterns
- Multi-region architectures with failover routing
The key distinction: AZ-305 asks you to choose between services with overlapping capabilities. Azure Front Door, Traffic Manager, Application Gateway, and Load Balancer all do traffic management — but for different layers, different scenarios, and different cost profiles. You need to know the decision tree cold.
How to structure your study
Weeks 1–2: Domain mapping Go through the Microsoft Learn AZ-305 learning path. Unlike AZ-104, don't try to lab everything — at expert level, many concepts are architectural rather than configurational. Focus on understanding the why behind service choices, not just the what.
Weeks 3–4: Case study practice AZ-305 case studies are the hardest part for most candidates. Find practice case studies and work through them methodically: read the requirements, list the constraints (cost, compliance, RTO/RPO, scale), then justify each architectural choice. Practice writing out your reasoning — even if the exam is multiple choice, working through the justification helps you eliminate wrong answers faster.
Week 5: Weak domain focus Run practice questions by domain. Almost everyone has a different weak area — for most it's either governance/policy or business continuity. Find yours early and close it.
Week 6: Timed full exams AZ-305 is mentally demanding. Case studies take 10–15 minutes each. Run two full timed exams in the final week to build the stamina to stay sharp through 120 minutes of architectural reasoning.
The most common reason people fail AZ-305
They approach it like AZ-104 — testing service knowledge rather than design judgment.
AZ-305 questions rarely have an obviously wrong answer. They have a best answer given the stated constraints. "Use Azure Front Door" might be correct for one scenario and wrong for another depending on the protocol, the traffic pattern, and the cost requirement in the brief.
The candidates who pass are those who practise making and justifying architectural decisions — not those who memorise which services exist.
Key resources
- Microsoft Learn AZ-305 path — free, official, well-structured
- John Savill's AZ-305 Study Cram on YouTube — excellent condensed review
- WhizLabs or MeasureUp practice exams — the closest to real exam question style
- ExamCoach — adaptive AZ-305 practice questions across all four design domains
Design thinking is a skill — practise it
The gap between understanding Azure and passing AZ-305 is the ability to apply that understanding to novel scenarios under time pressure. ExamCoach gives you AZ-305 practice questions across all four design domains, tracks where your correct rate drops, and surfaces your weakest areas so you can close them before exam day.
Start practising AZ-305 free →
ExamCoach covers AZ-305, AZ-104, AZ-204, AWS CLF-C02, CCNA, CISSP, CFA Level 1, and more.