ANS-C01 Network Management and Operations Practice Question

A network engineer is troubleshooting intermittent connectivity issues between two VPCs that are peered. The VPC peering connection is in the 'active' state. ICMP ping from an instance in VPC A to an instance in VPC B fails intermittently. What is the most likely cause?

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The route tables in one or both VPCs lack routes to the peer VPC's CIDR via the peering connection.

Since the VPC peering connection is active, the issue is likely that the route tables in one or both VPCs are not correctly configured to route traffic to the peered VPC's CIDR via the peering connection. Without proper routes, traffic is dropped.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The network ACLs are blocking ICMP traffic.
Why it's wrong here
Network ACLs would block consistently, not intermittently.
✗
The security groups on the instances do not allow inbound ICMP.
Why it's wrong here
Security groups are stateful and would block consistently, not intermittently.
✗
The VPC peering connection is not in the 'active' state.
Why it's wrong here
The question states it is active, so this is not the cause.
✓
The route tables in one or both VPCs lack routes to the peer VPC's CIDR via the peering connection.
Why this is correct
Intermittent issues could be due to route propagation delays, but typical cause is missing routes.

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ANS-C01 Network Management and Operations Practice Question

Why each option matters

Option-by-option breakdown

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