You are troubleshooting a connectivity issue between two compute instances within the same VCN.
Both instances are in different subnets. Instance A (IPv4: 10.0.1.10, IPv6: fc00:1:1::10) can ping its
subnet gateway (10.0.1.1) and can ping the IPv6 address of Instance B (fc00:1:2::20), but cannot ping
Instance B's IPv4 address (10.0.2.20). The security lists and network security groups (NSGs) are
configured to allow all traffic between the subnets. The route table for Instance A’s subnet has a rule
to route all traffic destined to 10.0.2.0/24 subnet to the VCN Local Peering Gateway. What is the
most probable cause?
B
Explanation:
Analyze Connectivity Successes: Instance A can ping its subnet gateway (10.0.1.1), indicating that
local subnet routing and security rules are functioning for IPv4. It can also ping Instance B’s IPv6
address (fc00:1:2::20), confirming that IPv6 routing and security rules between subnets are
operational.
Identify the Failure: Instance A cannot ping Instance B’s IPv4 address (10.0.2.20). Since security lists
and NSGs allow all traffic, the issue is unlikely to be a security configuration problem.
Examine Routing for Instance A: The route table for Instance A’s subnet (10.0.1.0/24) has a rule
directing traffic to 10.0.2.0/24 via the VCN Local Peering Gateway (LPG). In OCI, LPGs are used for
intra-region VCN peering, but here, both instances are in the same VCN, so this rule is likely a
misconfiguration or irrelevant unless peering is involved. However, the successful IPv6 ping suggests
basic connectivity exists.
Check Return Path from Instance B: For a ping to succeed, Instance B must send ICMP replies back to
Instance A (10.0.1.10). Instance B’s subnet (10.0.2.0/24) needs a route table entry to send traffic to
10.0.1.0/24. Without this, replies are dropped, causing the IPv4 ping to fail. The IPv6 success
indicates that IPv6 routing is correctly configured both ways, possibly via SLAAC or default routes.
Evaluate Options:
A: Incorrect. IPv6 is enabled, as Instance A pings Instance B’s IPv6 address.
B: Correct. Missing route for 10.0.1.0/24 in Instance B’s subnet prevents IPv4 replies.
C: Incorrect. Security lists and NSGs can filter IPv6 traffic in OCI.
D: Incorrect. Ping supports IPv6, as evidenced by the successful IPv6 ping.
The most probable cause is a missing route in Instance B’s subnet route table. In OCI, each subnet
has its own route table, and for instances in different subnets within the same VCN to communicate,
both subnets must have appropriate routes. The successful IPv6 ping suggests that IPv6 routing is
intact (likely due to default behavior or SLAAC), but IPv4 requires explicit routing. Per the Oracle
Networking Professional study guide, "Route tables must be configured to direct traffic to the
appropriate next hop for inter-subnet communication within a VCN" (OCI Networking
Documentation, Section: Virtual Cloud Networks).
Reference: Oracle Cloud Infrastructure Documentation - Networking Overview, Route Tables.
You are designing a backup solution in OCI. Compute instances in a private subnet need to back up
data to OCI Object Storage. Security policy mandates that data transfer must not traverse the public
internet. You need to choose the most secure and cost-effective method for accessing Object
Storage. Which endpoint/gateway configuration should you implement?
C
Explanation:
Requirement Analysis: The solution must ensure private access to Object Storage without public
internet traversal, while being cost-effective.
Evaluate OCI Components:
Internet Gateway: Provides public internet access, unsuitable for private connectivity.
NAT Gateway: Allows outbound internet access from private subnets, but traffic still exits OCI.
Service Gateway: Enables private access to OCI services like Object Storage within the same region.
DRG with FastConnect: Used for on-premises connectivity, not intra-OCI service access.
Option Assessment:
A: Uses public internet, violating the security policy.
B: HTTPS encrypts data, but traffic traverses the internet via NAT, violating the policy.
C: Service Gateway keeps traffic within OCI’s private network, meeting security and cost goals.
D: Overly complex and costly, with public endpoints contradicting the requirement.
Conclusion: Service Gateway with regional Object Storage endpoints ensures private, secure, and
cost-effective access.
The Service Gateway is designed for private access to OCI services like Object Storage, avoiding the
public internet. The Oracle Networking Professional study guide states, "A Service Gateway allows
instances in a private subnet to access supported OCI services without an Internet Gateway or NAT
Gateway, ensuring traffic remains within the Oracle network" (OCI Networking Documentation,
Section: Service Gateway). Using the Oracle Services Network service CIDR label for the region
ensures compatibility with Object Storage endpoints, optimizing cost and security.
Reference: Oracle Cloud Infrastructure Documentation - Service Gateway.
Your company has established a hybrid cloud environment using FastConnect to connect your on-
premises network to your OCI VCN. You are advertising on-premises network prefixes to OCI via BGP.
You want to ensure that OCI only learns routes from your on-premises network that are within a
specific range, and that any other prefixes advertised are rejected to prevent routing conflicts. Which
BGP attribute and configuration on the OCI side should you use to achieve this?
D
Explanation:
Objective: Filter BGP routes on OCI to accept only specific on-premises prefixes.
BGP Attributes Overview:
AS Path Prepending: Lengthens AS path to influence route preference, not filtering.
MED: Influences exit point selection, not route acceptance.
RD/RT: Used in MPLS VPNs for tenant isolation, not simple prefix filtering.
Prefix Lists: Directly filter prefixes based on IP ranges.
Evaluate Options:
A: AS Path Prepending affects preference, not filtering; unsuitable.
B: MED influences path selection, not route rejection; incorrect.
C: RD/RT is for VPN contexts, not applicable here.
D: Prefix Lists explicitly allow/deny prefixes, meeting the requirement.
Conclusion: Prefix Lists on the FastConnect virtual circuit provide precise control over accepted
routes.
Prefix Lists are the most effective BGP tool for filtering routes in OCI. The Oracle Networking
Professional study guide notes, "Prefix Lists can be applied to FastConnect virtual circuits to filter BGP
advertisements, ensuring only approved prefixes are learned by OCI" (OCI Networking
Documentation, Section: FastConnect and BGP). This prevents routing conflicts by rejecting
unwanted prefixes, aligning with the security and control requirements.
Reference: Oracle Cloud Infrastructure Documentation - FastConnect, BGP Configuration.
Which OCI service or feature enables the enforcement of granular, identity-based access controls for
packet routing, crucial for implementing Zero Trust principles?
C
Explanation:
Zero Trust Principles: Require explicit, identity-based access controls at every network stage.
Evaluate OCI Services:
Internet Gateway: Enables public internet access, no identity-based control.
Service Gateway: Provides private service access, no granular routing control.
NSGs: Offer stateful, identity-based rules at the VNIC level.
DRG: Facilitates routing, not identity-based access control.
NSG Fit: NSGs allow rules based on VNIC identity, source/destination IP, and ports, aligning with Zero
Trust.
Conclusion: NSGs are the best fit for granular, identity-based routing control.
NSGs are pivotal for Zero Trust in OCI. The Oracle Networking Professional study guide states,
"Network Security Groups provide granular, stateful security rules that can be applied to specific
VNICs, enabling identity-based access controls essential for Zero Trust architectures" (OCI
Networking Documentation, Section: Network Security Groups). Unlike security lists (subnet-level),
NSGs offer instance-level precision.
Reference: Oracle Cloud Infrastructure Documentation - Network Security Groups.
You are using Terraform to deploy a multi-tier application architecture consisting of a public subnet
hosting a load balancer, a private subnet hosting application servers, and another private subnet
hosting a database. The Terraform code successfully creates all the required infrastructure, including
route tables and security lists. However, after deployment, you realize that the load balancer cannot
reach the application servers in the private subnet. You have verified that the load balancer is healthy
and the application servers are running. What is the most likely cause of this connectivity problem?
A
Explanation:
Problem Scope: Load balancer (public subnet) cannot reach application servers (private subnet).
Connectivity Flow: Load balancer initiates traffic to application servers; application servers respond.
Key checkpoints: routing and security rules.
Analyze Routing: Private subnets typically don’t route to an Internet Gateway by default; they use
NAT or Service Gateways. Misrouting (Option B) would affect outbound traffic, not inbound from the
load balancer.
Security Rules:
Ingress (App Servers): Must allow traffic from the load balancer’s IP range.
Egress (Load Balancer): Must allow traffic to the application servers.
Evaluate Options:
A: Missing ingress rule on application servers’ security list blocks load balancer traffic; most likely.
B: Incorrect default route affects outbound, not inbound; less likely.
C: NAT misconfiguration impacts outbound, not inbound; incorrect.
D: Load balancer egress is necessary but secondary to application server ingress.
Conclusion: Ingress rule absence on the application server subnet is the primary blocker.
Security lists control traffic at the subnet level in OCI. The Oracle Networking Professional study
guide explains, "For a load balancer in a public subnet to communicate with instances in a private
subnet, the private subnet’s security list must include an ingress rule allowing traffic from the load
balancer’s IP range" (OCI Networking Documentation, Section: Security Lists). Since Terraform
deployed the infrastructure, a misconfigured security list is a common oversight.
Reference: Oracle Cloud Infrastructure Documentation - Security Lists.
When configuring transitive routing with a DRG across multiple VCNs and on-premises networks,
which key configuration step ensures that traffic from one VCN is correctly routed through the DRG
to an on-premises destination?
B
Explanation:
Transitive Routing Goal: Traffic from a VCN to an on-premises network via DRG.
DRG Role: Acts as a virtual router connecting VCNs and on-premises networks.
Routing Options:
Static Routes: Manually defined, less scalable for dynamic environments.
Dynamic Routing (BGP): Automatically exchanges routes, ideal for hybrid setups.
Evaluate Options:
A: Static routes work but require manual updates; less efficient.
B: BGP dynamically propagates routes, ensuring correct routing; best fit.
C: LPG is for intra-region peering, not on-premises connectivity; incorrect.
D: Service Gateway is for OCI services, not on-premises; incorrect.
Conclusion: BGP ensures scalable, accurate routing through the DRG.
The DRG supports transitive routing with dynamic protocols like BGP. The Oracle Networking
Professional study guide states, "For transitive routing between VCNs and on-premises networks via
a DRG, configuring BGP on the DRG and CPE enables automatic route propagation, ensuring traffic is
correctly routed" (OCI Networking Documentation, Section: Dynamic Routing Gateway). BGP is
preferred over static routes for hybrid cloud scenarios.
Reference: Oracle Cloud Infrastructure Documentation - Dynamic Routing Gateway.
In a complex multi-region OCI environment using DRGs for transitive routing, which method is most
efficient for ensuring that route updates from on-premises networks are propagated to all connected
VCNs?
B
Explanation:
Objective: Efficiently propagate on-premises route updates to multiple VCNs.
DRG Capabilities: Supports route distribution to attached VCNs.
Analyze Options:
A: Manual updates are inefficient and error-prone; unsuitable.
B: Centralized DRG with route distribution automates propagation; efficient.
C: Multiple DRGs add complexity and manual effort; inefficient.
D: Service Gateway is for OCI services, not route updates; incorrect.
Conclusion: Centralized DRG with route distribution is the most efficient method.
Route distribution in a DRG simplifies multi-region routing. The Oracle Networking Professional study
guide notes, "Using a centralized DRG with route distribution enabled allows routes learned from on-
premises networks to be automatically propagated to all attached VCNs, reducing management
overhead" (OCI Networking Documentation, Section: DRG Route Distribution). This leverages OCI’s
automation capabilities.
Reference: Oracle Cloud Infrastructure Documentation - DRG Route Distribution.
Your organization is deploying a critical database application on OCI. To ensure high availability, you
have deployed the database instances across multiple availability domains (ADs) within a single
region. You need to distribute client connections to the database instances and ensure that the load
balancer can handle long-lived TCP connections with minimal overhead. Session persistence is not
required. Which OCI load balancing solution would you choose in this scenario to minimize latency
and connection establishment overhead?
B
Explanation:
Requirements: Low-latency, minimal overhead for TCP connections, no session persistence.
Load Balancer Types:
Application Load Balancer (ALB): Layer 7, higher overhead, suited for HTTP/HTTPS.
Network Load Balancer (NLB): Layer 4, low overhead, ideal for TCP/UDP.
Evaluate Options:
A: ALB with HTTP checks is for HTTP traffic, adds overhead; unsuitable.
B: NLB with TCP checks is optimized for TCP, low latency; best fit.
C: ALB with TCP checks still has Layer 7 overhead; less efficient.
D: “Flexible Load Balancer” isn’t a specific OCI service; incorrect.
Conclusion: NLB minimizes latency and overhead for TCP connections.
The Network Load Balancer is designed for high-performance TCP scenarios. The Oracle Networking
Professional study guide states, "Network Load Balancer operates at Layer 4, providing low-latency,
high-throughput load balancing for TCP/UDP traffic with minimal overhead, ideal for database
connections" (OCI Networking Documentation, Section: Load Balancing). TCP health checks ensure
instance availability without session persistence complexity.
Reference: Oracle Cloud Infrastructure Documentation - Network Load Balancer.
You are designing a highly available web application on OCI. The application needs to be accessible
globally with traffic being routed to the nearest region based on user location. Additionally, you need
to implement sophisticated traffic management policies, such as A/B testing and weighted traffic
distribution based on application version. You also require protection against DDoS attacks. Which
OCI load balancing solution is best suited for these requirements?
C
Explanation:
Requirements: Global access, geo-routing, advanced traffic management, DDoS protection.
Load Balancer Options:
Regional LB: Single-region, no global routing or advanced policies.
NLB: Layer 4, no HTTP-based traffic management or DDoS features.
Global LB with Steering Policies: Layer 7, supports geo-routing and policies.
Flexible LB: Not a specific OCI service.
Assess Fit:
A: Lacks global and advanced features; unsuitable.
B: No Layer 7 or DDoS protection; incorrect.
C: Meets all requirements with geo-routing, steering policies, and WAF integration; best fit.
D: Non-existent service; incorrect.
Conclusion: Global LB with steering policies is the best solution.
The Global Load Balancer with Traffic Management Steering Policies supports global applications.
The Oracle Networking Professional study guide explains, "Global Load Balancer enables geo-based
routing and advanced traffic policies like A/B testing and weighted distribution, integrating with OCI
WAF for DDoS protection" (OCI Networking Documentation, Section: Load Balancing - Traffic
Management). This aligns with all specified requirements.
Reference: Oracle Cloud Infrastructure Documentation - Traffic Management.
You are configuring a VCN with multiple subnets for a customer. The security team requires that all
instances have IPv6 addresses. You configure the VCN with an IPv6 ULA CIDR block of fc00:1:1::/48
and create two private subnets. After launching instances in the two private subnets, you notice that
they only have IPv4 addresses assigned. You have not manually configured any IPv6 addresses on the
instances themselves. What steps are necessary to ensure the instances automatically receive IPv6
addresses?
B
Explanation:
Problem: Instances lack IPv6 addresses despite VCN IPv6 configuration.
OCI IPv6 Behavior: IPv6 requires subnet enablement and OS support via SLAAC.
Evaluate Options:
A: Incorrect. OCI doesn’t auto-assign IPv6 without OS configuration.
B: Correct. SLAAC must be enabled on the instance OS for auto-assignment.
C: Incorrect. IPv6 works in both public and private subnets.
D: Incorrect. IPv4 and IPv6 assignments are independent.
Conclusion: Enabling SLAAC on the OS ensures automatic IPv6 assignment.
IPv6 in OCI relies on SLAAC for automatic address assignment. The Oracle Networking Professional
study guide states, "To enable IPv6 on instances, the VCN and subnet must have IPv6 CIDR blocks,
and the instance OS must support SLAAC to automatically configure IPv6 addresses" (OCI Networking
Documentation, Section: IPv6 Configuration). Without SLAAC, instances default to IPv4 only.
Reference: Oracle Cloud Infrastructure Documentation - IPv6 Networking.
You are troubleshooting an issue where legitimate users are occasionally blocked by your OCI WAF,
which is configured in "Detection" mode. You need to identify the specific WAF rules that are
triggering these false positives and adjust them without disrupting legitimate traffic. Which approach
offers the most efficient way to diagnose and resolve this issue?
A
Explanation:
Problem Scope: Identify and adjust WAF rules causing false positives in Detection mode without
disrupting traffic.
Detection Mode Behavior: Logs potential violations without blocking, allowing analysis.
Evaluate Options:
A: Use OCI Logging Analytics to pinpoint rule IDs from logs, then set rules to "log only" for testing;
efficient and non-disruptive.
B: Disabling all rules risks security and is time-consuming; inefficient.
C: Increasing sensitivity worsens false positives; counterproductive.
D: Whitelisting IPs is a temporary fix, not scalable or diagnostic; unsuitable.
Conclusion: Logging analysis with rule adjustment is the most efficient approach.
OCI WAF logs provide detailed insights for troubleshooting. The Oracle Networking Professional
study guide states, "In Detection mode, WAF logs all triggered rules, which can be analyzed in OCI
Logging Analytics to identify false positives. Rules can then be adjusted to 'log only' to refine policies
without affecting traffic" (OCI Networking Documentation, Section: Web Application Firewall). This
method ensures precision and minimal disruption.
Reference: Oracle Cloud Infrastructure Documentation - Web Application Firewall.
When configuring a network appliance within a VCN to enable transitive routing, which of the
following is essential to ensure traffic flows correctly between interconnected VCNs?
B
Explanation:
Objective: Enable transitive routing via a network appliance (e.g., firewall) between VCNs.
Transitive Routing Setup: DRG connects VCNs; appliance processes traffic.
Key Requirement: DRG must route traffic to the appliance’s private IP.
Evaluate Options:
A: Service Gateway is for OCI services, not transitive routing; incorrect.
B: Static routes on DRG to appliance ensure correct traffic flow; essential.
C: Load Balancer is optional, not essential for routing; incorrect.
D: LPG is for intra-region VCN peering, not appliance-DRG connection; incorrect.
Conclusion: DRG static routes to the appliance are critical for transitive routing.
Transitive routing with a network appliance requires explicit routing configuration. The Oracle
Networking Professional study guide notes, "To enable transitive routing through a network
appliance, configure static routes in the DRG route table pointing to the appliance’s private IP as the
next hop" (OCI Networking Documentation, Section: Transitive Routing with DRG). This ensures
traffic is processed by the appliance between VCNs.
Reference: Oracle Cloud Infrastructure Documentation - Dynamic Routing Gateway.
Your company has a FastConnect circuit established between your on-premises data center and OCI.
However, you have a specific regulatory requirement to encrypt all traffic, even over dedicated
connections like FastConnect. You need to implement IPSec encryption without significantly
impacting the available bandwidth of your FastConnect circuit. Which is the most effective approach
to implement IPSec encryption over your existing FastConnect circuit, while maintaining high
bandwidth?
A
Explanation:
Requirements: Encrypt FastConnect traffic with minimal bandwidth impact.
IPSec Options:
DRG VPN: Native OCI solution over FastConnect.
Firewall Appliances: Adds overhead and complexity.
Compute Instances: Resource-intensive, not scalable.
Internet VPN: Uses public internet, against requirements.
Evaluate Options:
A: DRG VPN with AES-GCM (low-overhead encryption) leverages FastConnect; optimal.
B: Firewalls with AES-256 add overhead, reducing bandwidth; less effective.
C: Compute-based VPN is inefficient and public-facing; unsuitable.
D: Public internet VPN violates privacy requirement; incorrect.
Conclusion: DRG VPN with AES-GCM is the most effective solution.
OCI supports IPSec over FastConnect via DRG. The Oracle Networking Professional study guide
explains, "A Site-to-Site VPN over FastConnect using the DRG provides encrypted traffic with low-
overhead algorithms like AES-GCM, maintaining high bandwidth" (OCI Networking Documentation,
Section: FastConnect with VPN). This meets regulatory and performance needs efficiently.
Reference: Oracle Cloud Infrastructure Documentation - Site-to-Site VPN over FastConnect.
You have deployed a distributed application across OCI and Azure. You have established the OCI-
Azure Interconnect. You are experiencing packet loss and performance degradation when
transmitting large volumes of data between the two cloud providers. You have verified that the
network devices on both sides are correctly configured. Which is NOT a typical root cause to
investigate when troubleshooting performance issues across the OCI-Azure Interconnect?
C
Explanation:
Problem: Packet loss and degradation over OCI-Azure Interconnect.
Typical Causes: Security rules, routing, MTU mismatches.
Evaluate Options:
A: NSGs/Security Lists blocking traffic is a common issue; typical.
B: Routing misconfiguration can drop packets; typical.
C: Pricing tiers affect billing, not interconnect bandwidth; not typical.
D: MTU mismatches cause fragmentation and loss; typical.
Conclusion: Pricing tiers are unrelated to interconnect performance issues.
Interconnect performance issues stem from network configuration, not pricing. The Oracle
Networking Professional study guide states, "Troubleshooting multi-cloud interconnects involves
checking security rules, routing, and MTU settings, as these directly impact traffic flow" (OCI
Networking Documentation, Section: Multi-Cloud Connectivity). Pricing tiers influence resource
limits, not interconnect bandwidth.
Reference: Oracle Cloud Infrastructure Documentation - OCI-Azure Interconnect.
You are managing a Site-to-Site VPN connection between your on-premises network and OCI. You
notice that the VPN tunnel is frequently dropping and re-establishing. You have verified the internet
connectivity at both ends and confirmed that the IKE (Internet Key Exchange) parameters are
correctly configured. Which of the following is the most likely cause of the intermittent VPN tunnel
disconnections?
C
Explanation:
Symptoms: VPN tunnel drops intermittently despite stable internet and IKE settings.
VPN Components: Requires IKE (UDP 500/4500) and ESP (IP 50) traffic.
Evaluate Options:
A: Incorrect CPE IP would prevent tunnel establishment, not intermittent drops; incorrect.
B: DRG outage would cause full downtime, not intermittent; unlikely.
C: Security rules blocking IKE/ESP intermittently (e.g., rate limiting) is common; most likely.
D: NAT-Traversal issues typically prevent initial setup, not intermittent drops; less likely.
Conclusion: Security rule misconfiguration is the most probable cause.
VPN stability depends on unblocked IKE and ESP traffic. The Oracle Networking Professional study
guide notes, "Intermittent VPN tunnel drops are often caused by security rules or firewalls blocking
IKE (UDP 500/4500) or ESP (IP Protocol 50) traffic" (OCI Networking Documentation, Section: Site-to-
Site VPN Troubleshooting). This aligns with the scenario’s symptoms.
Reference: Oracle Cloud Infrastructure Documentation - Site-to-Site VPN.