Networking questions in the AZ-305 exam are often scenario-based and can be tricky because multiple services overlap in functionality. This capsule highlights common mistakes to avoid, exam strategies, and quick reference mappings.
Common Pitfalls
1. VNet Peering vs VPN Gateway
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VNet Peering → connects VNets over Azure backbone (fast, private).
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VPN Gateway → encrypted tunnel over the internet.
Exam Trap: If scenario mentions latency-sensitive communication between VNets in Azure, the answer is VNet Peering, not VPN.
2. Peering Non-Transitivity
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VNet peering is non-transitive by default.
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If A ↔ B and B ↔ C, A cannot reach C unless you design hub-and-spoke.
Exam Trap: Don’t assume A-B-C works automatically.
3. NSGs vs Firewall
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NSG = subnet/NIC-level, rule-based filtering.
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Firewall = centralized, stateful, enterprise-grade filtering.
Exam Trap: If centralized inspection across multiple VNets is required, pick Firewall, not NSGs.
4. Private Endpoint vs Service Endpoint
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Service Endpoint = keeps traffic on Azure backbone, but service still public.
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Private Endpoint = service gets private IP, no public exposure.
Exam Trap: If compliance requires no public access at all, correct answer = Private Endpoint.
5. Application Gateway vs Front Door
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App Gateway = regional, works within one Azure region.
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Front Door = global, latency-based routing with edge presence.
Exam Trap: If question says multi-region failover or global distribution, the answer is Front Door, not App Gateway.
6. Load Balancer vs App Gateway
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Load Balancer = Layer 4 (TCP/UDP).
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App Gateway = Layer 7 (HTTP/HTTPS, WAF).
Exam Trap: If SSL termination or path-based routing is required, App Gateway is correct.
Exam Strategies
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Look for keywords in the scenario
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“Global distribution, low latency” → Azure Front Door.
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“Centralized firewalling across VNets” → Azure Firewall.
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“Isolate PaaS service from public internet” → Private Endpoint.
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“Distribute VM traffic, TCP/UDP” → Load Balancer.
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Don’t over-engineer
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If requirement is simple VM load distribution, don’t choose App Gateway or Front Door.
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If compliance is not mentioned, default Microsoft-managed security may be enough.
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Combine services where appropriate
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Front Door + Application Gateway → global entry + regional WAF.
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Firewall + NSGs → centralized + local filtering.
Quick Recall Table
| Requirement | Best Solution |
|---|---|
| Fastest connectivity between VNets | VNet Peering |
| Encrypted hybrid connection | VPN Gateway |
| Private, high-bandwidth hybrid link | ExpressRoute |
| Centralized firewalling | Azure Firewall |
| Subnet-level filtering | NSGs |
| Isolate PaaS service (SQL/Storage) | Private Endpoint |
| Route /api vs /media traffic | Application Gateway |
| Global low-latency distribution | Azure Front Door |
| Cache static content globally | Azure CDN |
| VM-level TCP/UDP load balancing | Azure Load Balancer |
Exam Tips
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Expect scenario questions where 2–3 services sound correct.
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Always tie the solution to the keyword: global, private, secure, regulatory, latency, centralized.
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Remember peering is not transitive — hub-and-spoke is the design pattern.
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If question mentions WAF (SQL injection/XSS protection) → Application Gateway or Front Door (WAF enabled).
What to Expect in the Exam
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Direct Q: “Which Azure service connects VNets using backbone network?” → VNet Peering.
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Scenario Q: “Company needs multi-region failover for web app.” → Front Door.
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Scenario Q: “Company requires private access to SQL without internet exposure.” → Private Endpoint.
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Trick Q: “Service Endpoints prevent public access to PaaS service.” → False (only Private Endpoints do).