1Z0-1072-25 Question 171
Single answerYour company has configured local VCN peering between two Virtual Cloud Networks (VCN1 and VCN2) in the same region. You want instances in Subnet A of VCN1 to communicate with instances in Subnet B of VCN2. You have created and attached a local peering gateway (LPG) in each VCN, but traffic still does not flow. Using Network Path Analyzer from an instance in Subnet A to an instance in Subnet B shows a 'Route not found' error at the final hop. Which step should you take next?
- A
Add an Internet Gateway to VCN2 and update the route table in Subnet B to point to the Internet Gateway for VCN1� CIDR
- B
Add a route table entry in VCN2� Subnet B to direct traffic for VCN1� CIDR to the local peering gateway
- C
Enable a NAT Gateway in VCN1 and configure a route table entry in Subnet A to use the NAT Gateway as the next hop for VCN2
- D
Reconfigure the subnets in both VCNs to use the same CIDR block for simplicity
Show answer and explanation
Correct answer: B
Explanation
When troubleshooting connectivity between peered VCNs using Network Path Analyzer, a 'Route not found' result often indicates a missing route rule. For local VCN peering, each VCN� route table must include an entry pointing the other VCN� CIDR to the local peering gateway. Refer to Oracle� documentation on local VCN peering best practices (https://docs.oracle.com/en-us/iaas/Content/Network/Tasks/localVCNpeering.htm) for detailed setup procedures and troubleshooting steps.
- A. Incorrect.
Option 1 is incorrect because an Internet Gateway is used for public internet connectivity, not for routing traffic to another private VCN via local peering. The Network Path Analyzer indicating 'Route not found' suggests the LPG path is not properly configured in the route table, not that internet access is required.
- B. Correct.
Option 2 is correct. For local VCN peering, each participating VCN must have a route rule in its route table directing traffic for the other VCN� CIDR to the local peering gateway. If the route is missing in VCN2� Subnet B route table, traffic to VCN1� CIDR will fail, triggering the 'Route not found' error.
- C. Incorrect.
Option 3 is incorrect because a NAT Gateway routes traffic to the internet. NAT Gateways do not facilitate private traffic routing between VCNs. The correct next hop for traffic to another VCN is the local peering gateway, not a NAT Gateway.
- D. Incorrect.
Option 4 is incorrect because using the same CIDR block across two different VCNs is not allowed in OCI and would cause overlapping IP address space issues. Additionally, this does not address the missing route rule for local VCN peering.