Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A web tier and a backend tier are deployed in separate subnets. Backend VMs are rebuilt regularly, so their private IP addresses change. The web tier must reach the backend on TCP 8443, and administrators do not want to update NSG rules whenever a backend VM is replaced. What should be used in the NSG rule?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
The backend subnet CIDR, because subnet ranges never change during VM rebuilds.
A subnet CIDR is broader than the individual backend members and does not model the application tier as cleanly as an ASG. It also does not solve later tier-to-tier reuse as well as security groups do.
B
Distractor review
The AzureLoadBalancer service tag, because it identifies internal traffic between tiers.
AzureLoadBalancer is only for Azure load balancer probe traffic. It does not represent the web tier or the backend tier in this scenario.
C
Best answer
Application security groups for both tiers, because they track the VMs even when IP addresses change.
Application security groups let you group NICs by application role instead of by changing IP addresses. By referencing ASG-Web as the source and ASG-Backend as the destination, the NSG rule stays stable when backend VMs are rebuilt or NICs are replaced. This is the most maintainable option for tier-based filtering on a fixed port.
D
Distractor review
A user-defined route to the backend subnet, because route tables follow the VM even if the IP changes.
Route tables control traffic forwarding, not security filtering. They cannot replace NSG rules for allowing a specific TCP port between tiers.
Common exam trap
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Technical deep dive
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
- CIDR notation defines the prefix length.
- Block size helps identify subnet boundaries.
- Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
- The required host count determines the smallest suitable subnet.
TExam Day Tips
- Write the block size before choosing the subnet.
- Check whether the question asks for hosts, subnets or a specific address range.
- Do not confuse /24, /25, /26 and /27 host counts.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A route table contains these entries: 10.0.0.0/8 with next hop Virtual appliance, and 10.1.1.0/24 with next hop Virtual network gateway. Which next hop will Azure use for traffic to 10.1.1.5?
Question 2
You are deploying a stateless web application on Azure virtual machines. The solution must automatically add and remove instances based on CPU demand and allow all instances to be managed as one logical group. Which Azure compute feature should you deploy?
Question 3
You are deploying a Windows Server VM for an internal app. The VM must support Secure Boot and vTPM later, its OS disk must survive host moves, and the team wants the lowest-cost managed disk tier that still behaves like a normal writable OS disk. Which two choices should you make? Select two.
Question 4
You need to deploy several identical virtual machines and ensure that the failure of a single Azure host does not affect all of them. Which feature should you use?
Question 5
You need to connect VNet-Hub and VNet-Spoke so that resources in both virtual networks can communicate privately over the Microsoft backbone. Both virtual networks are in the same region. What should you configure?
Question 6
You need to create a storage account that provides the lowest-cost redundant storage for non-critical data and only needs protection against local disk or server failure within a single datacenter. Which redundancy option should you choose?
FAQ
Questions learners often ask
What does this AZ-104 question test?
CIDR notation defines the prefix length.
What is the correct answer to this question?
The correct answer is: Application security groups for both tiers, because they track the VMs even when IP addresses change. — Application security groups are designed for this exact problem: tier-based network filtering when VM IP addresses are not stable. By assigning the web VMs and backend VMs to ASGs, the NSG can refer to the groups rather than individual IPs or subnet ranges. That keeps the rule accurate when VMs are rebuilt and eliminates frequent manual updates to security rules. Why others are wrong: Using the subnet CIDR is broader than necessary and ties the rule to network layout instead of application role. AzureLoadBalancer does not represent tier-to-tier application traffic. A user-defined route only changes forwarding behavior and cannot permit or deny TCP 8443 traffic. The goal is security filtering that follows the workload, which is what ASGs provide.
What should I do if I get this AZ-104 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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