Every journey on the internet begins with a name. Before a browser can load a website, a user’s device must translate the human-readable domain name (like example.com) into a machine-readable IP address. This critical function is handled by the Domain Name System (DNS).
When operating a modern, cloud-native application, you need a DNS service that is as fast, global, and scalable as your infrastructure.
This is where Google Cloud DNS shines.
Google Cloud DNS is a high-performance, globally available, managed DNS service built on the same infrastructure that powers Google’s massive global network. It offers both public DNS serving for external domains and private DNS zones for internal VPC network resolution. By relying on Google’s low-latency, anycast network, Cloud DNS ensures your users find your applications quickly and reliably, regardless of where they are in the world.
Key Points You Will Master:
The core differences between Public and Private DNS zones.
How Cloud DNS achieves global availability and near-zero latency.
A direct comparison with AWS Route 53 and Azure DNS.
Designing a DNS strategy for a high-availability 2-tier application.
1. What is Google Cloud DNS?
Google Cloud DNS is a managed service for publishing and resolving domain names using Google's worldwide network of DNS name servers. It provides highly reliable and cost-effective resolution capabilities.
Cloud DNS operates in two primary modes:
Public DNS Zones: These host your public domain names (e.g.,
mywebsite.com) and are accessible to anyone on the internet. They are used to direct external traffic to your web servers, load balancers, or CDN endpoints.Private DNS Zones: These are used for internal name resolution within your Virtual Private Cloud (VPC) networks. They allow your Compute Engine VMs, GKE Pods, and Cloud Functions to communicate with each other using easily manageable internal names (e.g.,
api-service.internal). This is crucial for microservices and secure internal communications.
Actionable Insight: Cloud DNS leverages Anycast technology, meaning the same IP addresses are advertised from numerous locations globally. When a user sends a query, it is automatically routed to the nearest available Google DNS server, minimizing latency.
2. Key Features of Google Cloud DNS
Cloud DNS offers a robust set of features optimized for enterprise-grade performance and integration within the Google Cloud ecosystem.
| Feature | Description | Benefit |
| Anycast Network | All name servers advertise the same IP addresses from over 200 locations globally. | Lowest Latency: DNS lookups are resolved from the closest point of presence (POP), ensuring maximum speed. |
| Managed & Serverless | No infrastructure to manage, scale, or patch. Google handles capacity planning and security. | Zero Operational Burden: Focus on application development, not DNS server maintenance. |
| DNSSEC (Security) | Domain Name System Security Extensions validate the origin of DNS data using cryptographic signatures. | Security: Protects against cache poisoning and other DNS spoofing attacks. |
| Private DNS | Allows internal-only zone resolution tied to specific VPC networks. | Simplified Internal Communication: Enables naming for microservices and cloud resources without using complex IP addresses. |
| Logging | Provides detailed records of DNS queries performed against your managed zones. | Troubleshooting & Auditing: Essential for diagnosing network issues and monitoring security. |
| External Integrations | Seamless integration with Cloud Load Balancing, Cloud CDN, and Compute Engine. | Simplified Cloud Setup: Automatically updates DNS records when integrated services scale or change IP addresses. |
3. Explain Architecture of Google Cloud DNS
The architecture of Cloud DNS is distributed across Google's massive global network, distinguishing between the resolution path and the management path.
Resolution Path (The Query)
Anycast Global Server: The DNS query from a user's local resolver is routed to the nearest Google DNS name server using Anycast routing. This ensures extremely low query latency (often < 10ms).
Global Cache & Database: The Google DNS server checks its global cache first. If the record is found, it's served immediately. If not, the server queries the internal Cloud DNS database.
Authoritative Answer: The authoritative answer is retrieved from the database, served to the user, and cached globally for future queries. This process is highly distributed and redundant.
Management Path (The Zone)
Managed Zone: A Managed Zone is the administrative container for all the records for a specific domain name (e.g.,
example.com).API/Console Updates: When an administrator creates or modifies an A, CNAME, or other record via the Google Cloud Console or API, the changes are written to the highly available, replicated Cloud DNS database.
Global Propagation: The change is automatically and rapidly propagated across all Google's global name servers. Cloud DNS is known for its fast propagation times (seconds, not minutes), ensuring that updates are live almost immediately worldwide.
4. What are the Benefits of Google Cloud DNS?
Adopting Cloud DNS offers core advantages centered on performance, simplicity, and integration.
Exceptional Query Performance: By leveraging the Anycast network and the global POPs, Cloud DNS boasts single-digit millisecond latency for DNS lookups globally, which is a key factor in overall application load time (the "DNS handshake" is the first step).
Massive Scalability: Built on the same infrastructure as Google Search, Cloud DNS automatically handles billions of queries per day without performance degradation or the need for user capacity planning.
Operational Simplicity: As a fully managed, serverless service, there is zero maintenance required. You simply create the zones and records, and Google manages the underlying infrastructure, security patches, and hardware maintenance.
Cost-Effectiveness: The service is priced based on the number of zones and the volume of queries, making it highly cost-efficient, especially for high-volume workloads.
Enhanced Security: Native support for DNSSEC provides cryptographic validation, protecting your users from malicious DNS routing.
5. Compare Google Cloud DNS with AWS and Azure Service
Cloud DNS competes directly with the managed DNS offerings from the other major cloud providers.
| Feature | Google Cloud DNS | AWS Route 53 | Azure DNS |
| Management | Fully Managed (Serverless) | Fully Managed (Serverless) | Fully Managed (Serverless) |
| Global Reach | Anycast Network (200+ POPs) | Anycast Network (100+ Edge Locations) | Global distribution |
| Traffic Steering | Limited (Basic Round Robin) | Advanced (Latency, Geolocation, Weighted, Failover) | Limited (Basic Round Robin) |
| Internal DNS | Private DNS Zones | Private Hosted Zones | Private DNS Zones |
| Key Advantage | Superior speed and propagation time due to integration with Google's core network. | Rich feature set for traffic routing/steering and integration with AWS health checks. | Deep integration with Azure infrastructure and VNets. |
Key Insight: While Route 53 offers a richer set of advanced routing policies (like geo-location routing), Cloud DNS is often chosen for its sheer speed, rapid propagation, and simplicity, benefiting from the sheer density and optimization of the Google network.
6. What are Hard Limits on Google Cloud DNS?
Cloud DNS limits are primarily quotas designed to prevent abuse and ensure service quality. Most of these limits are soft (adjustable) and can be increased upon request.
| Resource/Limit Type | Default Limit/Note |
| Managed Public Zones per project | 250 zones |
| Managed Private Zones per project | 100 zones |
| Resource Record Sets per Managed Zone | 10,000 records |
| Queries per second per zone | 5,000 QPS (Queries Per Second) |
| Queries per second per project | 100,000 QPS |
Actionable Tip: For high-volume applications expecting traffic peaks, review the QPS limits for your project and request an increase proactively to ensure the service can handle sudden traffic surges.
7. Explain Top 10 Real World Use Cases Scenario on Google Cloud DNS
Cloud DNS is the cornerstone of modern network infrastructure, enabling essential cloud-native use cases.
Global Application Routing: Using a public zone's simple round-robin A record to direct traffic to multiple Cloud Load Balancer IPs deployed across different regions, providing basic global load distribution.
Disaster Recovery (DR) Failover: Manually updating the A record to point from the primary load balancer IP to the standby DR site IP in case of a regional outage.
Microservices Internal Discovery: Using a Private DNS zone tied to the VPC to allow GKE microservices to resolve each other by name (e.g.,
billing-service.internal) instead of internal cluster IPs.Hybrid Cloud Resolution: Setting up DNS Peering to allow DNS queries to be resolved between a VPC network and an on-premises network (via Cloud VPN/Interconnect), facilitating hybrid connectivity.
Reverse DNS Lookups: Creating PTR records, particularly for email servers, to prevent outgoing emails from being flagged as spam.
CDN Integration: Pointing a domain's CNAME record to the generated address of Cloud CDN to ensure static content is served from the edge network.
Subdomain Management: Easily delegating subdomains (e.g.,
blog.example.com,api.example.com) to separate, independent managed zones or external DNS services.Automated Record Creation: Integrating Cloud DNS with a deployment pipeline (like Jenkins or Cloud Build) to automatically update DNS records upon new environment creation or blue/green deployments.
Securing DNS: Enabling DNSSEC on public domains to ensure data integrity and authenticity, building user trust.
VPN/VPC Resolution: Using a DNS Forwarding Zone to route queries that originate inside the VPC to external, on-premises DNS resolvers for domains that are not managed by Google Cloud.
8. Explain in Detail Google Cloud DNS Availability, Resilience and Scalability
Cloud DNS is a prime example of Google's resilient infrastructure design.
Availability (High Uptime)
Global Anycast: By advertising the same DNS server IPs globally, the service ensures that if one specific point of presence (POP) goes offline, traffic is instantly and automatically rerouted to the next nearest POP. This makes the service resilient to localized network failures and ensures near-100% uptime.
Redundant Database: The core authoritative DNS database where zone records are stored is highly replicated and distributed across Google’s infrastructure, preventing a single point of failure in the management plane.
Resilience (Fault Tolerance)
Fast Propagation: Changes to DNS records propagate globally in seconds. This resilience factor is critical for Disaster Recovery (DR). When a disaster occurs, manually updating the A record to a DR IP takes effect almost instantaneously worldwide, minimizing the Recovery Time Objective (RTO).
Decoupled Resolution: The resolution plane (the servers answering queries) is completely decoupled from the management plane (the database accepting updates), ensuring that administrator errors or maintenance on the management side do not disrupt active query resolution.
Scalability (Handling Demand)
Unlimited QPS (Theoretical): While project quotas exist, the underlying Anycast architecture is designed to handle virtually unlimited queries per second (QPS). The load is automatically and seamlessly distributed across Google's massive global server footprint, eliminating the need for users to provision or manage DNS query capacity.
Simple Record Scaling: The ability to manage 10,000 records per zone and up to 250 zones per project (default) provides administrative scalability for even the largest enterprises.
9. Explain Step-by-Step Design on Google Cloud DNS for 2-Tier Web Application with Code Example in Python
A 2-tier web application needs both public resolution (for the load balancer) and private resolution (for the backend communication).
Design Overview
Public Tier (Frontend): A Global External Load Balancer needs a public domain name (
frontend.example.com).Private Tier (Backend): The frontend VMs/Pods need to talk to the database (
db-api.internal) using a Private DNS name.
Step 1: Set up Public DNS Zone and Record (Frontend)
This step assumes you have a public domain (example.com) registered and its NS records point to Google’s name servers.
# dns_public_setup.py - Public DNS Zone Management
from google.cloud import dns
PROJECT_ID = "your-gcp-project-id"
PUBLIC_ZONE_NAME = "example-com-public"
FRONTEND_DOMAIN = "frontend.example.com." # Note the trailing dot
LOAD_BALANCER_IP = "34.120.10.200" # Replace with your Load Balancer's IP
client = dns.Client(project=PROJECT_ID)
zone = client.zone(PUBLIC_ZONE_NAME)
# --- 1. Create a public A Record ---
change = zone.changes()
change.add_record(
FRONTEND_DOMAIN,
"A",
300, # TTL in seconds (5 minutes)
[LOAD_BALANCER_IP]
)
change.create()
print(f"Created A record for {FRONTEND_DOMAIN} pointing to {LOAD_BALANCER_IP}")
Step 2: Set up Private DNS Zone and Record (Backend)
This zone is only visible inside your designated VPC network.
# dns_private_setup.py - Private DNS Zone Management
from google.cloud import dns
PROJECT_ID = "your-gcp-project-id"
VPC_NETWORK_URL = "https://www.googleapis.com/compute/v1/projects/your-gcp-project-id/global/networks/default"
PRIVATE_ZONE_NAME = "internal-zone"
INTERNAL_DOMAIN = "db-api.internal." # Note the trailing dot
DATABASE_PROXY_IP = "10.0.1.5" # Internal IP of your database proxy/service
client = dns.Client(project=PROJECT_ID)
# --- 1. Create a Private Zone tied to the VPC ---
private_zone = client.zone(
PRIVATE_ZONE_NAME,
domain=INTERNAL_DOMAIN,
description="Private zone for internal services",
visibility="private",
# Link the zone to the VPC network
networks=[{"network_url": VPC_NETWORK_URL}]
)
private_zone.create()
# --- 2. Create a private A Record within the zone ---
change = private_zone.changes()
change.add_record(
INTERNAL_DOMAIN,
"A",
60, # Low TTL for internal services
[DATABASE_PROXY_IP]
)
change.create()
print(f"Created Private DNS zone and A record for {INTERNAL_DOMAIN}")
10. Refer Google blog with link on Google Cloud DNS
For the latest architectural deep dives, feature announcements, and best practices regarding Cloud DNS performance and configuration, always refer to the official source.
Google Cloud Blog: Networking Category:
https://cloud.google.com/blog/topics/networking https://medium.com/@kevinp11/how-to-have-http-s-redirect-with-gcp-cloud-dns-bef4e9b58388
11. Final Conclusion
Google Cloud DNS is the invisible, yet indispensable, foundation of any successful application on Google Cloud. By harnessing the power of Google’s Anycast global network, it delivers unparalleled speed and resilience for both public and private domain resolution. Its serverless model and deep integration with the rest of the GCP ecosystem (Load Balancer, Compute Engine, GKE) eliminate operational overhead, allowing your team to focus on innovation. For developers and architects prioritizing low latency, robust security (DNSSEC), and effortless scalability, Cloud DNS is the definitive choice for managing domain resolution at cloud scale.
13. List down 50 good Google Cloud DNS knowledge practice questions with 4 options and answer with an explanation
These questions are designed to test knowledge specific to Cloud DNS's features, types, architecture, and operational concepts.
Section 1: Fundamentals and Types (Q1-Q15)
Q1. What is the key technology Cloud DNS uses to route queries to the nearest name server globally?
A. Geo-location steering
B. Load balancing
C. Anycast
D. VPC Peering
Answer: C. Anycast routes a user's query to the geographically closest server advertising the same IP address.
Q2. What is the primary difference between a Public DNS Zone and a Private DNS Zone?
A. Public zones are free, private zones are paid.
B. Public zones use A records, private zones use CNAME.
C. Public zones are accessible globally; private zones are only resolvable within specified VPC networks.
D. Public zones require DNSSEC; private zones do not.
Answer: C. Private zones ensure internal name resolution remains private and secure.
Q3. Which resource record type is used to map a domain name to an IPv4 address?
A. CNAME
B. PTR
C. A
D. NS
Answer: C. An A record (Address record) maps a hostname to an IPv4 address.
Q4. What is the primary benefit of enabling DNSSEC on a public Cloud DNS zone?
A. Faster propagation time.
B. Protection against DNS cache poisoning and data spoofing.
C. Lower query costs.
D. Automatic IP address updates.
Answer: B. DNSSEC cryptographically validates the origin of DNS data.
Q5. The TTL (Time to Live) value on a DNS record dictates:
A. The number of queries allowed per second.
B. How long a resolver should cache the record before querying again.
C. The maximum size of the record set.
D. The zone's update frequency.
Answer: B. A lower TTL speeds up updates but increases query traffic.
Q6. Which type of record is used for reverse DNS lookups (mapping an IP address back to a hostname)?
A. AAAA
B. TXT
C. PTR
D. CNAME
Answer: C. A PTR (Pointer record) is used for reverse mapping, often for email validation.
Q7. Which Cloud DNS feature is essential for microservices deployed on GKE to communicate using friendly names?
A. Public DNS
B. Private DNS
C. DNS Logging
D. DNSSEC
Answer: B. Private DNS zones allow secure, internal-only name resolution.
Q8. What happens to a DNS query sent to a Cloud DNS name server if the server's cache does not contain the answer?
A. The query is rejected.
B. The server queries the internal Cloud DNS authoritative database.
C. The user's browser must resolve the query.
D. The query is forwarded to a public resolver.
Answer: B. The server retrieves the authoritative answer from the replicated internal database.
Q9. Which resource record type is used to map an alias domain name to a canonical domain name?
A. A
B. NS
C. CNAME
D. SRV
Answer: C. CNAME (Canonical Name record) creates an alias.
Q10. What is the primary method used to verify a change made to a managed zone in Cloud DNS?
A. Checking the service status.
B. Running a health check.
C. Viewing the Change history within the zone.
D. Checking the billing console.
Answer: C. Cloud DNS tracks all record modifications in the Change history.
Q11. What is a Managed Zone in the context of Cloud DNS?
A. A single DNS record.
B. An administrative container for all DNS records for a single domain.
C. The DNS name server.
D. A firewall rule.
Answer: B. The Managed Zone holds all the configurations for the domain.
Q12. What are the Cloud DNS servers called that are accessible globally and respond to queries?
A. Controllers
B. Tablets
C. Name Servers
D. Load Balancers
Answer: C. These are the authoritative name servers for your domain.
Q13. Cloud DNS is often noted for its exceptionally fast propagation. This means:
A. The service is cheap.
B. The time it takes for a record update to become globally active is very short (seconds).
C. The query speed is fast.
D. The TTL is always low.
Answer: B. Fast propagation is a key benefit, crucial for rapid updates.
Q14. What is the default maximum number of Resource Record Sets allowed per Managed Zone?
A. 100
B. 1,000
C. 10,000
D. 100,000
Answer: C. 10,000 records per zone is the default quota.
Q15. The DNS Forwarding feature in Cloud DNS is primarily used to:
A. Forward public traffic to the closest server.
B. Route specific internal queries (from VPC) to an external or on-premises DNS resolver.
C. Implement weighted routing.
D. Forward records between managed zones.
Answer: B. It enables hybrid cloud resolution for specific domains.
Section 2: Architecture, Comparison, and Use Cases (Q16-Q30)
Q16. In the Cloud DNS architecture, where are changes made by the administrator initially written?
A. Directly to the name server.
B. To the local client cache.
C. To the highly available, replicated Cloud DNS database.
D. To the VPC network configuration.
Answer: C. The database is the single source of truth before global propagation.
Q17. Which AWS service is the direct competitor to Google Cloud DNS?
A. AWS ALB
B. AWS S3
C. AWS Route 53
D. AWS CloudFront
Answer: C. Route 53 is AWS's managed DNS service.
Q18. What key routing feature does AWS Route 53 offer that Cloud DNS does NOT natively support?
A. A record creation.
B. Geolocation and Latency-based traffic steering.
C. DNSSEC.
D. Private zones.
Answer: B. Cloud DNS relies on GCLB for advanced traffic steering, not native DNS features.
Q19. For a 2-tier application's public frontend, which Cloud DNS zone type must be used?
A. Private zone.
B. Internal zone.
C. Public zone.
D. Forwarding zone.
Answer: C. Public zones expose the domain name to the internet.
Q20. When running a GKE microservice, why is a Private DNS Zone preferable to using GKE’s ClusterIP for internal communication?
A. It is faster.
B. It provides stable, human-readable names across the entire VPC, not just within the cluster.
C. It is more secure.
D. It supports more protocols.
Answer: B. Private DNS simplifies naming conventions across different VPC resources (VMs, services, etc.).
Q21. How does Cloud DNS handle scalability for query traffic?
A. By requiring the user to request more QPS manually.
B. By limiting the number of zones.
C. By distributing the load automatically across the massive, redundant Anycast network.
D. By relying on the Load Balancer.
Answer: C. The Anycast architecture provides seamless, automatic scaling for queries.
Q22. Which record type is necessary to ensure secure email delivery when setting up a mail server?
A. AAAA
B. PTR
C. TXT (for SPF/DKIM)
D. SRV
Answer: B. PTR records enable reverse DNS, a requirement for many modern mail servers to prevent spam flagging.
Q23. Which Cloud DNS feature is critical for minimizing the Recovery Time Objective (RTO) during a disaster?
A. High TTL.
B. Fast propagation time.
C. PTR records.
D. DNS Logging.
Answer: B. The ability to change the DR IP quickly ensures the application recovers rapidly.
Q24. When integrating Cloud DNS with Cloud Load Balancing, the DNS record typically points to the Load Balancer's:
A. Backend service name.
B. External Forwarding Rule IP address.
C. Target proxy URL.
D. Internal subnet.
Answer: B. The external IP of the Forwarding Rule is the public entry point.
Q25. Which Azure service is the direct equivalent of Google Cloud DNS?
A. Azure Traffic Manager
B. Azure Front Door
C. Azure DNS
D. Azure Load Balancer
Answer: C. Azure DNS is their managed DNS service.
Q26. What is the recommended TTL (Time to Live) for a public domain's A record pointing to a frequently updated Load Balancer?
A. 1 day
B. 1 hour
C. 5 minutes (300 seconds)
D. 1 week
Answer: C. A low TTL allows rapid cache expiration and speeds up updates/failovers.
Q27. When viewing a DNS query log in Google Cloud, what is the key piece of information Cloud DNS Logging provides?
A. The cost of the query.
B. The source IP of the resolver and the resolved record.
C. The firewall rule used.
D. The CPU usage of the name server.
Answer: B. Query logging is vital for troubleshooting and security auditing.
Q28. What is the maximum number of Managed Public Zones allowed per project by default?
A. 50
B. 100
C. 250
D. 1,000
Answer: C. The default quota is 250.
Q29. What is the typical latency achieved by Cloud DNS queries due to the Anycast network?
A. Over 100 ms
B. 50-100 ms
C. Single-digit milliseconds (< 10 ms)
D. Seconds
Answer: C. The use of a dense global Anycast network ensures very low latency.
Q30. What is the key advantage of using DNS Peering between a VPC and an on-premises network?
A. Enables automatic failover.
B. Simplifies SSL certificate management.
C. Allows resources in the VPC to resolve names managed by the on-premises DNS server and vice-versa.
D. Automatically updates A records.
Answer: C. DNS Peering facilitates name resolution across hybrid cloud boundaries.
Section 3: Operations and Resilience (Q31-Q50)
Q31. Which of the following is NOT a benefit of using a low TTL for a public DNS record?
A. Faster propagation of changes.
B. Quicker failover capability.
C. Reduced query costs.
D. Less aggressive caching by resolvers.
Answer: C. A lower TTL increases query volume and thus increases query costs.
Q32. If you want to delegate a subdomain (e.g., dev.example.com) to an external DNS provider, which record type must you create in your Cloud DNS zone?
A. A
B. CNAME
C. NS
D. SOA
Answer: C. The NS (Name Server) record delegates authority for the subdomain.
Q33. What is the primary difference between A records and AAAA records?
A. A records are public, AAAA records are private.
B. A records are for mail, AAAA records are for web.
C. A records map to IPv4, AAAA records map to IPv6.
D. A records are required for DNSSEC.
Answer: C. AAAA is the IPv6 equivalent of the A record.
Q34. What record type defines the administrative information and primary name server for a DNS zone?
A. NS
B. A
C. SOA
D. TXT
Answer: C. The SOA (Start of Authority) record is mandatory and defines zone parameters.
Q35. What is the primary resilience factor of the Cloud DNS service itself?
A. Node Auto-Repair.
B. The globally distributed, highly redundant Anycast network.
C. Connection draining.
D. Automated SSL certificates.
Answer: B. The core architecture ensures the service is resilient to failure.
Q36. When performing a maintenance action on a public domain, what is the first DNS step an administrator should take to prepare for quick failover?
A. Delete the zone.
B. Lower the TTL of the A record.
C. Enable DNSSEC.
D. Create a private zone.
Answer: B. Lowering the TTL forces resolvers to query for fresh data more frequently.
Q37. Which GCP service is required to enable DNS Forwarding (e.g., routing queries to an on-premises server)?
A. Cloud Load Balancing
B. Cloud VPN or Cloud Interconnect
C. Cloud CDN
D. Cloud Functions
Answer: B. Connectivity must be established first via VPN or Interconnect.
Q38. Why is Cloud DNS considered a serverless service?
A. It only runs functions.
B. Because users do not manage, provision, or patch any underlying servers or infrastructure.
C. It only handles internal traffic.
D. It is free of charge.
Answer: B. The serverless model eliminates infrastructure management.
Q39. When creating a Private DNS Zone, what is the critical step to ensure it resolves names correctly?
A. Enabling DNSSEC.
B. Setting the TTL to 60 seconds.
C. Linking the zone to one or more VPC networks.
D. Creating a CNAME record.
Answer: C. Private zones are linked to VPCs for scope control.
Q40. The cost of Cloud DNS is primarily calculated based on:
A. The number of instances in the VPC.
B. The total GB of data transferred.
C. The number of managed zones and the volume of queries served.
D. The number of record sets.
Answer: C. Billing is per zone and per million queries.
Q41. Which record type is used to verify domain ownership (e.g., for SSL validation or email security)?
A. SOA
B. AAAA
C. TXT
D. SRV
Answer: C. TXT records hold arbitrary text strings, commonly used for verification (like SPF or DKIM).
Q42. If a query is sent to a Cloud DNS server, and the record's TTL has not expired, the query is likely served from the:
A. Authority server.
B. Global cache.
C. Resolver.
D. Cloud CDN.
Answer: B. Caching ensures fast resolution until the TTL expires.
Q43. Which DNS setting must you update with your domain registrar when using a Public Cloud DNS zone?
A. TTL
B. A record
C. PTR record
D. NS records
Answer: D. You must update the Name Server (NS) records to point to the Google DNS servers.
Q44. What is the theoretical maximum QPS (Queries Per Second) that the Cloud DNS architecture is designed to handle?
A. 1,000 QPS.
B. 100,000 QPS.
C. Virtually unlimited, due to auto-scaling over the global network.
D. Limited by the Forwarding Rule.
Answer: C. Its architecture is built for Google-scale traffic.
Q45. When moving an application to a new Compute Engine VM within the same Private DNS zone, which record type needs updating?
A. CNAME (of the host)
B. A (of the host)
C. NS
D. PTR (if reverse DNS is needed)
Answer: B. The A record points to the new VM's internal IP address.
Q46. Which record type is used to define the location of services like SIP or XMPP?
A. A
B. TXT
C. SRV
D. CNAME
Answer: C. SRV records specify the location (port and host) of services.
Q47. If the propagation time is slow for your public record updates, what is the most likely cause?
A. The TTL is set too low.
B. The DNS caches worldwide are honoring an old, high TTL set previously.
C. The Private DNS zone is conflicting.
D. The network firewall is blocking the update.
Answer: B. High TTL on previous records delays propagation even if the current TTL is low.
Q48. The separation of the Resolution Path and Management Path in Cloud DNS contributes primarily to:
A. Lower cost.
B. High resilience and service uptime during administrative changes.
C. Faster DNSSEC validation.
D. Better integration with Compute Engine.
Answer: B. Changes don't affect live query serving.
Q49. For a 2-tier application's database, the Private DNS record should use a low TTL (e.g., 60 seconds) because:
A. It is a security requirement.
B. Internal services often require quick updates or failover, minimizing service disruption.
C. Low TTL is free.
D. It prevents the network from failing.
Answer: B. Low TTL is a best practice for internal, rapidly changing service endpoints.
Q50. Cloud DNS uses a single Anycast IP globally. How does the internet route a user's query to the correct server?
A. By checking the user's geolocation in a database.
B. Using BGP (Border Gateway Protocol) routing to find the nearest advertising point-of-presence.
C. By relying on the user's ISP.
D. Via a Load Balancer in the user's region.
Answer: B. BGP routing is the underlying internet protocol that directs traffic to the nearest Anycast advertisement.
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