The correct architecture is to configure a Cloud DNS forwarding zone for on-premises names and a private zone for GCP names, then create an inbound server policy for on-premises to query Cloud DNS. This works because the inbound server policy allows on-premises DNS resolvers to send queries for private zone names like `gcp.internal` into Cloud DNS over the Cloud VPN with BGP, while the forwarding zone directs GCP VMs to resolve on-premises hostnames like `corp.example.com` by forwarding those queries to the on-premises DNS servers. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding of hybrid DNS resolution without exposing DNS to the internet—a common trap is forgetting that inbound server policies are required for on-premises-to-Cloud DNS queries, not just forwarding zones. Remember the memory tip: “Forward out, inbound in”—forwarding zones send queries out of GCP, inbound server policies bring queries into GCP.
PCNE Configuring network services Practice Question
This PCNE practice question tests your understanding of configuring network services. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 company is migrating an on-premises DNS service to Cloud DNS. They want to resolve on-premises hostnames from GCP VMs and resolve Google Cloud private zone names from on-premises. They have a Cloud VPN with BGP. Which architecture should they implement?
Configure a Cloud DNS forwarding zone for on-premises names and a private zone for GCP names. Then create an inbound server policy for on-premises to query Cloud DNS.
Inbound server policy allows on-premises to resolve private zones; forwarding zone allows GCP to resolve on-premises.
B
Configure a split-horizon DNS with separate DNS servers for each environment.
Why wrong: This is not scalable; Cloud DNS integration is the recommended approach.
C
Set up Cloud DNS peering zones between the VPC and on-premises.
Why wrong: DNS peering only works within Google Cloud.
D
Use DNS over HTTPS from on-premises to Google's public DNS.
Why wrong: Public DNS does not resolve private zone names.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure a Cloud DNS forwarding zone for on-premises names and a private zone for GCP names. Then create an inbound server policy for on-premises to query Cloud DNS.
Option A is correct because Cloud DNS supports inbound server policies that allow on-premises DNS resolvers to forward queries for private zone names (e.g., `gcp.internal`) to Cloud DNS via the Cloud VPN. A forwarding zone in the VPC directs queries for on-premises hostnames (e.g., `corp.example.com`) to the on-premises DNS servers. This bidirectional resolution is achieved without exposing DNS to the internet, leveraging BGP for routing.
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.
✓
Configure a Cloud DNS forwarding zone for on-premises names and a private zone for GCP names. Then create an inbound server policy for on-premises to query Cloud DNS.
Why this is correct
Inbound server policy allows on-premises to resolve private zones; forwarding zone allows GCP to resolve on-premises.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure a split-horizon DNS with separate DNS servers for each environment.
Why it's wrong here
This is not scalable; Cloud DNS integration is the recommended approach.
✗
Set up Cloud DNS peering zones between the VPC and on-premises.
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the distinction between DNS peering (VPC-to-VPC) and DNS forwarding/inbound policies (VPC-to-on-premises), causing candidates to mistakenly choose peering for hybrid scenarios.
Detailed technical explanation
How to think about this question
An inbound server policy creates a VPC-scoped inbound DNS endpoint with a regional internal IP address that on-premises resolvers can target. The forwarding zone uses a list of on-premises DNS server IPs (reachable via VPN) and supports conditional forwarding based on the DNS suffix. Under the hood, Cloud DNS uses BGP-learned routes to ensure the inbound endpoint IP is reachable from on-premises, and the forwarding zone queries are sent over UDP/53 with standard DNS recursion.
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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Configuring network services — This question tests Configuring network services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure a Cloud DNS forwarding zone for on-premises names and a private zone for GCP names. Then create an inbound server policy for on-premises to query Cloud DNS. — Option A is correct because Cloud DNS supports inbound server policies that allow on-premises DNS resolvers to forward queries for private zone names (e.g., `gcp.internal`) to Cloud DNS via the Cloud VPN. A forwarding zone in the VPC directs queries for on-premises hostnames (e.g., `corp.example.com`) to the on-premises DNS servers. This bidirectional resolution is achieved without exposing DNS to the internet, leveraging BGP for routing.
What should I do if I get this PCNE 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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company has a Cloud VPN tunnel to on-premises. They want on-premises clients to resolve private DNS names in the VPC. Which service should they configure?
easy
✓ A.Inbound DNS policy
B.Outbound DNS policy
C.Cloud NAT
D.Private Google Access
Why A: Option C is correct: An inbound DNS policy forwards DNS queries from on-premises DNS servers to Cloud DNS, enabling resolution of private zone names. Option A is for outbound internet; Option B only gives VMs access to Google APIs; Option D is for VMs to forward queries to on-premises.
Variation 2. A company is migrating on-premises DNS to Google Cloud. They have a hybrid network using Cloud VPN and want to resolve on-premises hostnames from Compute Engine instances without custom scripts. Which service should they use?
hard
✓ A.Use Cloud DNS inbound server policy to forward queries to on-premises DNS.
B.Create a forwarding zone in Cloud DNS and associate it with the VPC.
C.Enable Private Google Access on the VPC subnet.
D.Configure Cloud NAT to forward DNS queries to on-premises DNS servers.
Why A: Cloud DNS inbound server policy allows on-premises DNS servers to receive DNS queries from Compute Engine instances by creating a VPC-scoped policy that forwards queries to the IP addresses of on-premises DNS resolvers over Cloud VPN. This enables hybrid name resolution without custom scripts, as the policy automatically handles the forwarding of DNS requests from Google Cloud resources to the on-premises DNS infrastructure.
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Question Discussion
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