Question 474 of 1,170
Implement and Manage Virtual NetworkingmediumMultiple ChoiceObjective-mapped

AZ-104 Implement and Manage Virtual Networking Practice Question

This AZ-104 practice question tests your understanding of implement and manage virtual networking. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A spoke VM can connect to a hub VM by IP address after peering is configured, but it cannot resolve internal host names such as app01.corp.local. The hub has a DNS server at 10.50.1.4 that hosts those records. What should the administrator configure so the spoke VMs use that DNS server?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Set the spoke VNet's custom DNS server to 10.50.1.4.

Option B is correct because the spoke VNet must be configured to use a custom DNS server to override Azure's default internal name resolution. By setting the spoke VNet's DNS server to 10.50.1.4, all VMs in the spoke will query that server for hostname resolution, including app01.corp.local. This is a VNet-level setting that applies to all VMs in the spoke, and it does not require any changes to NSGs or peering configurations.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

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

  • Add an NSG rule allowing UDP and TCP port 53 between the VNets.

    Why it's wrong here

    Port 53 may be required for DNS traffic, but it does not tell the spoke where to send queries.

    When this WOULD be correct

    An administrator configures VNet peering but cannot connect to the hub VM by IP address. The hub VM has a firewall blocking inbound DNS traffic. Adding an NSG rule allowing UDP/TCP 53 on the hub subnet would permit the spoke VMs to reach the hub's DNS server.

  • Set the spoke VNet's custom DNS server to 10.50.1.4.

    Why this is correct

    The spoke VNet must be told to use the DNS server that contains the internal zone records. By configuring 10.50.1.4 as the custom DNS server for the spoke VNet, new and existing VMs in that VNet can query the hub-based resolver for names such as app01.corp.local. Peering alone does not change DNS behavior, so the DNS server setting is the missing configuration.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Create a private endpoint for the hub DNS server.

    Why it's wrong here

    Private endpoints are for Azure PaaS services, not for exposing a standard DNS server as a private service.

    When this WOULD be correct

    An administrator needs to securely connect to an Azure SQL Database from a spoke VNet using a private IP address, avoiding public internet exposure. In that scenario, creating a private endpoint for the SQL Database in the hub VNet would be correct.

  • Enable remote gateways on the spoke peering.

    Why it's wrong here

    Remote gateways are for routing through an existing gateway, not for name resolution between VNets.

    When this WOULD be correct

    This option would be correct in a scenario where the hub VNet has a VPN gateway or ExpressRoute gateway, and the spoke VNet needs to use that gateway to access on-premises resources or the internet. The question would specify that the spoke VMs need to route traffic through the hub's gateway.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AZ-104 exam frequently reuses these exact scenarios with slightly different constraints.

Set the spoke VNet's custom DNS server to 10.50.1.4.Correct answer

Why this is correct

The spoke VNet must be told to use the DNS server that contains the internal zone records. By configuring 10.50.1.4 as the custom DNS server for the spoke VNet, new and existing VMs in that VNet can query the hub-based resolver for names such as app01.corp.local. Peering alone does not change DNS behavior, so the DNS server setting is the missing configuration.

Add an NSG rule allowing UDP and TCP port 53 between the VNets.Wrong answer — click to see why

Why this is wrong here

The issue is DNS resolution, not network connectivity. NSG rules control traffic flow, but the spoke VNet still uses its default Azure DNS, not the hub's DNS server. Adding NSG rules for port 53 does not change the DNS server configuration.

★ When this WOULD be the correct answer

An administrator configures VNet peering but cannot connect to the hub VM by IP address. The hub VM has a firewall blocking inbound DNS traffic. Adding an NSG rule allowing UDP/TCP 53 on the hub subnet would permit the spoke VMs to reach the hub's DNS server.

Why candidates choose this

Candidates often confuse connectivity issues with DNS resolution. Since DNS uses port 53, they assume that allowing this port via NSG will fix name resolution, overlooking that the VNet's DNS server setting must be changed first.

Create a private endpoint for the hub DNS server.Wrong answer — click to see why

Why this is wrong here

A private endpoint is used to securely access Azure PaaS services (like Azure SQL, Storage) over a private IP within a VNet, not to configure DNS resolution for VMs. It does not set a custom DNS server for a VNet.

★ When this WOULD be the correct answer

An administrator needs to securely connect to an Azure SQL Database from a spoke VNet using a private IP address, avoiding public internet exposure. In that scenario, creating a private endpoint for the SQL Database in the hub VNet would be correct.

Why candidates choose this

Candidates may confuse private endpoints with DNS resolution because both involve private IPs and name resolution, but private endpoints are for PaaS services, not for setting DNS servers for VMs.

Enable remote gateways on the spoke peering.Wrong answer — click to see why

Why this is wrong here

Enabling remote gateways on the spoke peering allows the spoke VNet to use the hub's VPN/ExpressRoute gateway for outbound connectivity, but it does not configure DNS settings. The spoke VMs still need a custom DNS server address to resolve internal host names.

★ When this WOULD be the correct answer

This option would be correct in a scenario where the hub VNet has a VPN gateway or ExpressRoute gateway, and the spoke VNet needs to use that gateway to access on-premises resources or the internet. The question would specify that the spoke VMs need to route traffic through the hub's gateway.

Why candidates choose this

Candidates may confuse the concept of using a hub's gateway for network connectivity with using a hub's DNS server for name resolution, assuming that enabling remote gateways also forwards DNS queries.

Analysis generated from the official AZ-104blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse VNet peering with DNS resolution, assuming that peering automatically enables name resolution across VNets, when in fact you must explicitly configure a custom DNS server or use Azure Private DNS Zones to resolve private hostnames.

Detailed technical explanation

How to think about this question

When you set a custom DNS server on a VNet, Azure updates the DHCP lease for all VMs in that VNet to include the custom DNS server's IP address as the primary DNS resolver. This is done at the Azure platform level, and VMs must reboot or renew their DHCP lease to pick up the change. In a hub-and-spoke topology, the hub DNS server (e.g., a Windows Server with AD DS) typically hosts internal zones like corp.local, and the spoke VMs must be configured to query it directly; VNet peering does not automatically propagate DNS settings.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

Visual reference

Client Recursive Resolver Root DNS (13 root servers) TLD DNS (.com, .org, …) Authoritative example.com query IP addr answer

Quick reference

Common DNS Record Types

RecordPurposeExample
AIPv4 address mappingexample.com → 93.184.216.34
AAAAIPv6 address mappingexample.com → 2606:2800::1
CNAMEAlias to another hostnamewww → example.com
MXMail server for domainexample.com → mail.example.com (priority 10)
TXTText data (SPF, DKIM, verification)v=spf1 include:_spf.example.com ~all
NSAuthoritative name serversexample.com NS ns1.example.com
PTRReverse DNS (IP → hostname)34.216.184.93.in-addr.arpa → example.com
SOAZone authority recordPrimary NS, admin email, serial, TTL defaults

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this AZ-104 question test?

Implement and Manage Virtual Networking — This question tests Implement and Manage Virtual Networking — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Set the spoke VNet's custom DNS server to 10.50.1.4. — Option B is correct because the spoke VNet must be configured to use a custom DNS server to override Azure's default internal name resolution. By setting the spoke VNet's DNS server to 10.50.1.4, all VMs in the spoke will query that server for hostname resolution, including app01.corp.local. This is a VNet-level setting that applies to all VMs in the spoke, and it does not require any changes to NSGs or peering configurations.

What should I do if I get this AZ-104 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jun 11, 2026

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