AZ-305 Design infrastructure solutions Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Use an Azure Load Balancer and configure NSGs on each subnet.

  Why it's wrong here

  Azure Load Balancer operates at Layer 4 (TCP/UDP) and only distributes traffic based on IP address and port rules. It cannot provide SSL termination, web application firewall (WAF) capabilities, or path-based routing, all of which are essential for protecting and properly routing HTTP(S) requests in a multi-tier web application. Configuring NSGs on each subnet adds basic network-level filtering, but NSGs alone cannot inspect or sanitize application-layer traffic, leaving the web tier vulnerable to SQL injection, XSS, and other OWASP threats. Therefore, this option is incorrect because it lacks the required Layer 7 features.

• ✗

  Use Azure Firewall to inspect all traffic and allow internet traffic to the web tier.

  Why it's wrong here

  Azure Firewall is a stateful firewall that operates at layers 3-4 with some layer 7 capabilities, but it is not optimized for inbound web traffic with SSL offloading and URL routing like a WAF-enabled service.

• ✓

  Use Azure Application Gateway with WAF, and configure NSGs to restrict traffic between tiers.

  Why this is correct

  Azure Application Gateway is a Layer 7 regional load balancer that provides SSL termination, WAF, URL-based routing, and cookie-based session affinity, making it the appropriate entry point for the web tier. By enabling WAF, it actively blocks common web vulnerabilities such as SQL injection and cross-site scripting before they reach the backend. Complementing this with NSGs on each subnet enforces network-level isolation, ensuring that only the web tier can communicate with the app tier on specific ports (e.g., 8080/tcp) and that the app tier cannot initiate outbound connections to the internet. This combination of application-layer protection and subnet-level access control exactly matches the requirement to restrict traffic between tiers while securely exposing the web tier.

• ✗

  Use Azure Front Door to expose the web tier and NSGs for internal isolation.

  Why it's wrong here

  Azure Front Door is incorrect because it is a global service designed for distributing traffic across multiple regions or public endpoints, whereas this scenario describes a multi-tier application primarily within a single virtual network. While Front Door offers SSL termination, WAF, and URL-based routing, its global scope is not the primary requirement for exposing a web tier residing regionally within a VNet. It would be appropriate for a globally distributed application requiring cross-region traffic management and acceleration.