PCNE Practice Test 2 — 30 Questions

Question 1

A company has a VPC with subnets in us-central1 and europe-west1. They create a Private Service Connect endpoint for a managed service in us-central1. Can Compute Engine instances in europe-west1 access the endpoint?

Accepted Answer

No, because the endpoint is only accessible from the same region.. Private Service Connect (PSC) endpoints are regional resources. An endpoint created in us-central1 is only accessible from Compute Engine instances within the same region (us-central1) of the VPC. Instances in europe-west1 cannot directly reach the endpoint because traffic would need to cross regional boundaries, which PSC does not support for producer endpoints. Option D correctly identifies this regional restriction.

Answer

Yes, if they use a global load balancer in front of the endpoint.

Answer

No, unless the VPC is peered with another VPC that contains the endpoint.

Answer

Yes, because the endpoint is accessible from any region in the VPC.

Question 2

A company has deployed a Global External Application Load Balancer with Premium Tier and enables Cloud CDN. Users in Europe report high latency, while users in the US have good performance. The backend is a regional NEG in us-west1. What is the most likely cause?

Accepted Answer

The origin server is sending 'Cache-Control: private' headers, preventing Cloud CDN from caching.. Option D is correct because Cloud CDN cannot cache responses that include a 'Cache-Control: private' header. This header instructs intermediate caches (including CDN nodes) not to store the response, forcing all requests to go to the origin server in us-west1. Users in Europe experience high latency because their requests must traverse the long distance to the US origin, while US users benefit from shorter paths. Enabling Cloud CDN alone does not guarantee caching; the origin must also allow caching by omitting 'private' or setting appropriate 'Cache-Control: public' and 'max-age' directives.

Answer

The load balancer is using Premium Tier, which routes to the nearest backend; the backend is only in us-west1.

Answer

Cloud CDN is not enabled on the load balancer.

Answer

The load balancer is using Standard Tier, which does not support global anycast.

Question 3

Which THREE actions should you take to secure a VPC that hosts public-facing web applications?

Accepted Answer

Use Cloud NAT to allow outbound internet access without public IPs. Cloud NAT enables outbound internet access for private VMs without assigning them public IP addresses, which reduces the attack surface. This is a secure alternative to direct internet access because it allows outbound connections initiated by the VMs while blocking unsolicited inbound traffic from the internet. It works by translating private IP addresses to a set of ephemeral public IPs managed by Google Cloud.

Answer

Assign public IP addresses to all VMs for direct internet access

Answer

Enable VPC Flow Logs to block malicious traffic

Question 4

A company is using Cloud NAT to allow private instances to access the internet. They notice that some instances are not able to reach certain external services. Which THREE steps should they take to troubleshoot?

Accepted Answer

Check if the external service is blocking the Cloud NAT IP addresses.. Option A is correct because Cloud NAT uses a set of public IP addresses for outbound traffic. If the external service has firewall rules or access control lists that block these specific IP addresses, the instances will be unable to reach it. Checking for IP-based blocking is a standard first step in troubleshooting connectivity issues through a NAT gateway.

Answer

Ensure that the VPC has a default route to the internet gateway.

Answer

Check the DNS resolution for the external service.

Question 5

A company is setting up a Dedicated Interconnect connection between their on-premises network and Google Cloud. They have configured a VLAN attachment and assigned a Cloud Router with BGP sessions. They notice that traffic is being dropped intermittently. The BGP session status shows 'Established' but routes are not being exchanged consistently. What is the most likely cause?

Accepted Answer

Bidirectional Forwarding Detection (BFD) is not enabled on the BGP session. When BFD is not enabled on a BGP session, the BGP keepalive timers (typically 60 seconds) are used to detect failures, which can cause intermittent traffic drops because BGP does not detect link failures quickly enough. With BFD enabled (default interval of 300ms), failures are detected in sub-seconds, preventing route flapping and ensuring consistent route exchange. The 'Established' BGP state with inconsistent route exchange is a classic symptom of BFD being absent, as routes may be withdrawn and re-advertised due to transient link issues that BGP alone cannot react to fast enough.

Answer

The on-premises firewall is blocking BGP port 179

Answer

The Cloud Router has reached the maximum number of routes

Answer

The MTU on the VLAN attachment is set too low

Question 6

A company needs to connect their on-premises data center to Google Cloud using Dedicated Interconnect. They have a service level agreement that requires 99.99% availability for the connection. What is the minimum number of VLAN attachments they must provision, and how should they be configured to meet this SLA?

Accepted Answer

Two VLAN attachments, each on a different Interconnect. To achieve 99.99% availability for Dedicated Interconnect, you must eliminate single points of failure. A single VLAN attachment on one Interconnect (Option A) provides no redundancy. Google Cloud requires at least two VLAN attachments, each on a different Interconnect (and ideally different edge availability domains), to meet this SLA. This ensures that if one Interconnect or VLAN attachment fails, traffic can fail over to the other, maintaining connectivity.

Answer

One VLAN attachment with a single Interconnect

Answer

Four VLAN attachments on two Interconnects

Answer

Two VLAN attachments on the same Interconnect

Question 7

A network engineer is troubleshooting a Cloud VPN tunnel that is not passing traffic. The tunnel status shows as established, and BGP sessions are up. However, traffic from an on-premises subnet (10.0.1.0/24) to a GCP subnet (192.168.1.0/24) is not working. What should the engineer check first?

Accepted Answer

Verify that the on-premises router is advertising the 10.0.1.0/24 prefix via BGP. Option A is correct because even though the VPN tunnel and BGP session are established, traffic may still fail if the on-premises router is not advertising the on-premises subnet (10.0.1.0/24) to GCP via BGP. Without this advertisement, GCP's Cloud Router has no route to reach that subnet, so return traffic from GCP to on-premises is dropped. The first step in troubleshooting is to verify that the on-premises BGP speaker is sending the correct prefix in its UPDATE messages.

Answer

Ensure that the Cloud Router is configured with the correct BGP ASN

Answer

Check that GCP has a static route for 10.0.1.0/24 pointing to the VPN tunnel

Answer

Check GCP firewall rules to allow ingress from 10.0.1.0/24

Question 8

A company is designing a VPC with multiple subnets across two regions for high availability. They want to ensure that instances in different regions can communicate using internal IP addresses without traversing the public internet. Which TWO actions should they take? (Choose two.)

Accepted Answer

Set up VPC peering between the VPCs in each region.. Option A is correct because VPC peering allows direct, private IP connectivity between two VPCs using the AWS global network backbone, without traversing the public internet. This enables instances in different regions to communicate using internal IP addresses, provided the VPCs have non-overlapping CIDR blocks and appropriate route table entries are configured.

Answer

Create firewall rules allowing all traffic from the other region's subnet CIDR.

Answer

Configure instances to use external IP addresses for cross-region communication.

Answer

Use a shared VPC to connect both regions.

Question 9

A company uses Cloud NAT to enable outbound internet access for private instances in a VPC. They notice that some instances are unable to connect to external services, while others can. The network team has verified that all instances have the same tags and are in the same subnet. Which TWO actions should the team take to troubleshoot the issue?

Accepted Answer

Check Cloud NAT logs for port exhaustion. Option B is correct because Cloud NAT logs can reveal port exhaustion, which occurs when the NAT gateway runs out of available source ports for connections. Since all instances share the same NAT IP addresses, high connection counts from some instances can exhaust ports, preventing others from establishing new outbound connections. Checking these logs helps identify whether port exhaustion is the root cause of the connectivity issue.

Answer

Ensure Cloud NAT is enabled in each zone where instances are located

Answer

Verify that the instances have external IP addresses assigned

Answer

Review the health check configuration for the NAT gateway

Question 10

A network engineer is setting up Dedicated Interconnect and sees the output above. What does the 'encryption: IPSEC' field indicate about this VLAN attachment?

Accepted Answer

Traffic over this VLAN attachment is encrypted using IPsec. The 'encryption: IPSEC' field in the VLAN attachment output for Dedicated Interconnect indicates that traffic traversing this attachment is encrypted using IPsec. This is a feature of Google Cloud's Dedicated Interconnect that allows you to enable IPsec encryption on the VLAN attachment itself, providing confidentiality and integrity for data in transit without requiring a separate Cloud VPN tunnel.

Answer

The attachment is using Cloud VPN as the underlying transport

Answer

The attachment requires a Cloud VPN tunnel in addition to the Interconnect

Answer

The attachment is using MACsec encryption at layer 2

Question 11

A company uses Cloud Armor to protect an HTTPS Load Balancer. They notice that legitimate traffic from a specific geographic region is being blocked. The security policy has a deny rule for that region. What is the correct way to allow traffic from that region while still protecting against attacks?

Accepted Answer

Add a new allow rule for that region with a lower priority number than the deny rule. Cloud Armor security rules are evaluated in order of priority, where a lower priority number means higher precedence. To allow traffic from a specific region that is currently blocked by a deny rule, you must add an allow rule with a lower priority number (e.g., 100) than the deny rule (e.g., 1000). This ensures the allow rule is evaluated first, permitting the legitimate traffic before the deny rule can block it, while the deny rule still protects against attacks from other regions.

Answer

Remove the deny rule for that region and rely on other security measures

Answer

Remove all rules and add a single allow rule for the legitimate region

Answer

Reorder the rules so that the deny rule is at the bottom of the list

Question 12

An organization wants to restrict access to a Cloud Storage bucket so that only VMs within a specific VPC network can download objects. They are using VPC Service Controls and Private Google Access. Which configuration is required?

Accepted Answer

Enable Private Google Access on the subnet and create a VPC Service Controls perimeter that includes the bucket project. D is correct because VPC Service Controls create a security perimeter around the Cloud Storage bucket's project, preventing data exfiltration even if the bucket is publicly accessible. Private Google Access on the subnet allows VMs to reach Google APIs (including storage.googleapis.com) via internal IPs, avoiding the public internet. Together, they ensure only VMs within the specified VPC network can download objects, as the perimeter restricts access to authorized networks and Private Google Access provides the private connectivity path.

Answer

Enable Cloud NAT and configure a firewall rule to allow egress to 0.0.0.0/0

Answer

Configure a Service Directory endpoint and attach an IAM policy to the bucket allowing access only from that endpoint

Answer

Create a firewall rule allowing egress to the storage.googleapis.com service IP range and enable VPC flow logs

Question 13

A company with a hub-and-spoke VPC topology uses Shared VPC and VPC Network Peering. They want to ensure that only specific VMs in a spoke project can connect to a database instance in the hub project. What is the most secure approach?

Accepted Answer

Use Private Service Connect to publish the database as a managed service and create a Private Service Connect endpoint in the spoke VPC with IAM permissions for the specific VM service accounts. Option C is correct because Private Service Connect (PSC) allows you to publish a managed service (like Cloud SQL) and create a PSC endpoint in the spoke VPC. By combining the PSC endpoint with IAM permissions on the VM service accounts, you ensure that only specific VMs can connect to the database, providing fine-grained, identity-aware access control without exposing the database to the entire network.

Answer

Deploy the Cloud SQL Auth Proxy on each VM and configure IAM permissions for each VM's service account

Answer

Use Shared VPC and assign the specific VMs to a subnet with a dedicated secondary IP range, then restrict database access to that range

Answer

Configure firewall rules in the hub project to allow traffic only from the specific VM internal IPs

Question 14

A company is using Cloud NAT for outbound internet access. They want to ensure that traffic from certain VMs always uses a specific set of NAT IPs for auditing purposes. Which three steps are necessary to achieve this? (Choose THREE.)

Accepted Answer

Ensure the VMs have a default route (0.0.0.0/0) with next hop set to the Cloud NAT gateway's subnet. Option A is correct because for Cloud NAT to function, the VM must have a default route (0.0.0.0/0) that points to the Cloud NAT gateway's subnet as the next hop. Without this route, the VM's outbound traffic will not be directed to the NAT gateway, and the NAT IPs will not be used. This ensures that traffic from the VM is routed through the NAT gateway, allowing the specific set of NAT IPs to be applied for auditing.

Answer

Configure IAM conditions on the Cloud NAT resource to restrict which VMs can use it

Answer

Enable VPC Flow Logs on the subnet to monitor which NAT IPs are used

Question 15

Refer to the exhibit. A user cannot SSH into test-vm from their workstation (public IP 203.0.113.5) using the VM's external IP 34.67.89.10. The firewall rule allow-ssh exists. What is the most likely cause?

Accepted Answer

The firewall rule allow-ssh is missing a source IP range or has a source IP range that does not include the user's IP. The most likely cause is that the firewall rule 'allow-ssh' is missing a source IP range or has a source IP range that does not include the user's public IP (203.0.113.5). In Google Cloud, firewall rules are stateful and by default deny all ingress traffic unless explicitly allowed; without a source IP range (or with an incorrect one), the SSH traffic from the user's workstation is dropped at the VPC firewall level, preventing access to the VM's external IP (34.67.89.10).

Answer

The firewall rule allow-ssh is for the wrong network

Answer

The firewall rule allow-ssh is disabled

Answer

The VM's external IP (34.67.89.10) is blocked by Cloud NAT

Question 16

Which TWO of the following are valid methods to reduce latency between users in Europe and a GCP-hosted application?

Accepted Answer

Use Cloud CDN to cache content at edge locations.. Cloud CDN uses Google's globally distributed edge caches to serve content from locations closer to users, reducing round-trip time and latency. For users in Europe, cached static or dynamic content is delivered from a nearby edge PoP, bypassing the need to fetch from the origin server in a potentially distant region.

Answer

Establish a Cloud VPN tunnel to the user's ISP.

Answer

Use Premium Tier networking instead of Standard Tier.

Answer

Use Cloud NAT for outbound traffic.

Question 17

Based on the exhibit, what is the purpose of Cloud Router's BGP configuration?

Accepted Answer

To advertise the VPC's IP range to the on-premises network.. Cloud Router uses BGP to dynamically exchange routes between a VPC network and an on-premises network over a VPN tunnel or Dedicated Interconnect. In this configuration, the purpose is to advertise the VPC's IP range (the custom or auto-mode subnet CIDR) to the on-premises router, enabling on-premises hosts to route traffic back to the VPC. This is achieved by configuring the Cloud Router with a BGP session and setting the advertised route for the VPC's IP range.

Answer

To load balance traffic across multiple VPN tunnels.

Answer

To receive a default route from the on-premises network.

Answer

To advertise a default route to the on-premises network.

Question 18

Which THREE of the following are requirements for implementing a Global External HTTP(S) Load Balancer with an external backend?

Accepted Answer

The backend must support health checks from the load balancer's health check IP ranges.. Option B is correct because Global External HTTP(S) Load Balancers use Google's frontend (proxying) IP ranges to send health checks to backends. The backend must allow inbound traffic from these specific health check IP ranges (e.g., 35.191.0.0/16 and 130.211.0.0/22) to receive health probes; otherwise, the load balancer will mark the backend as unhealthy and stop forwarding traffic.

Answer

The backend must be configured with Private Google Access.

Answer

The backend must have an SSL certificate installed.

Question 19

A company is deploying an internal load balancer (ILB) in a VPC to distribute traffic among backend instances in a managed instance group. The ILB should only be accessible from within the VPC. Which of the following is a required step when configuring the ILB?

Accepted Answer

Specify a subnet in the same region as the backend instances.. An internal load balancer (ILB) in GCP requires a regional forwarding rule that routes traffic to backend instances within the same VPC. Specifying a subnet in the same region as the backend instances is mandatory because the ILB's internal IP address is allocated from that subnet, and the forwarding rule must reference a subnet to enable internal-only routing. Without a subnet, the ILB cannot be provisioned as an internal load balancer.

Answer

Assign a static external IP address to the forwarding rule.

Answer

Upload an SSL certificate to the load balancer.

Answer

Create a Cloud NAT gateway for the backend instances.

Question 20

A company is planning to migrate their on-premises application to Google Cloud. The application requires consistent high bandwidth and low latency to on-premises databases. They have a Dedicated Interconnect connection with a 10 Gbps link. To improve availability, they decide to add a second Interconnect connection. Which of the following is a best practice for configuring BGP sessions?

Accepted Answer

Configure two BGP sessions, each on a separate connection, with different ASNs and MED values to influence path selection. Option B is correct because using different ASNs on each BGP session allows the on-premises router to treat the two Dedicated Interconnect connections as separate routing peers, enabling path selection control via MED values. This ensures that if one connection fails, traffic can be rerouted through the other, improving availability without relying on ECMP or a single session, which would not provide the desired redundancy and traffic engineering.

Answer

Configure two BGP sessions with the same ASN and MED values

Answer

Enable ECMP across the two connections with a single BGP session

Answer

Use a single BGP session across both connections