Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A company has a hub virtual network that contains a custom DNS server at 10.20.0.4. A new spoke virtual network is peered to the hub. VMs in the spoke can reach other resources in Azure, but they cannot resolve internal names such as app01.corp.local. What should the administrator configure to fix name resolution for the spoke VMs?
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
Add a user-defined route that sends DNS traffic to the hub virtual network.
Routes control packet forwarding, but they do not tell Azure which DNS server to use for name resolution.
B
Best answer
Set the spoke virtual network's custom DNS server to 10.20.0.4.
This directs VMs in the spoke to query the hub DNS server for internal names. In a hub-and-spoke design, peering alone does not make Azure use a custom DNS server automatically. Configuring the spoke VNet to use 10.20.0.4 ensures clients send DNS queries to the server that already hosts the corporate zone records.
C
Distractor review
Create an NSG rule that allows UDP port 53 from the spoke subnet to the hub subnet.
An NSG can permit DNS traffic, but it does not configure which DNS server the VMs should query.
D
Distractor review
Enable gateway transit on the hub peering so name resolution flows through the VPN gateway.
Gateway transit is for shared gateway routing to on-premises networks, not for selecting a DNS server in Azure.
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: Set the spoke virtual network's custom DNS server to 10.20.0.4. — The spoke VNet must be configured to use the custom DNS server IP so its VMs know where to send name resolution requests. Peering does not automatically inherit DNS settings, and Azure-provided DNS will not know about internal corporate zones. Setting the spoke VNet's DNS server to 10.20.0.4 is the standard fix when a hub hosts authoritative internal name resolution. Why others are wrong: A user-defined route cannot change DNS server selection. NSG rules can permit or block the DNS port, but they do not provide name resolution configuration. Gateway transit helps spokes use the hub's VPN or ExpressRoute gateway for routed connectivity to on-premises networks; it does not make Azure resolve names through the gateway.
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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