The correct answer is that the instance is communicating with both internal and internet hosts. This is determined by interpreting VPC Flow Logs, which capture metadata about IP traffic to and from network interfaces; here, the logs show the EC2 instance at 10.0.1.5 sending and receiving traffic to an internal IP (10.0.2.10) on port 443 and to an external IP (203.0.113.50) on port 80, both with ACCEPT records, confirming successful bidirectional flows to internal and internet destinations. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this tests your ability to read flow log fields like srcaddr, dstaddr, and action, and to distinguish between internal RFC 1918 addresses and public IPs—a common trap is assuming all traffic to port 80 is internet-bound, but you must check the destination IP range. Memory tip: think “two IPs, two ports, all ACCEPT” to quickly confirm hybrid connectivity.
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The instance is communicating with both internal and internet hosts
The VPC Flow Logs show the EC2 instance (10.0.1.5) communicating with both an internal IP (10.0.2.10) on port 443 and an external IP (203.0.113.50) on port 80, with ACCEPT records for both flows. This indicates successful bidirectional traffic to both internal and internet hosts, confirming option D is correct.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 instance is not communicating with the internet
Why it's wrong here
Logs show traffic to 203.0.113.5 (internet).
✗
The instance's security group is blocking traffic
Why it's wrong here
All traffic is ACCEPTED.
✗
The instance is only communicating with another instance in the same subnet
Why it's wrong here
Also communicates with internet IP.
✓
The instance is communicating with both internal and internet hosts
Why this is correct
Logs show internal (10.0.1.8) and internet (203.0.113.5) traffic.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that any traffic to a non-RFC 1918 IP automatically implies internet access, but the trap here is that candidates may overlook the ACCEPT status and assume security group blocking, or misinterpret internal IPs as being in the same subnet when they are not.
Trap categories for this question
Command / output trap
Logs show traffic to 203.0.113.5 (internet).
Detailed technical explanation
How to think about this question
VPC Flow Logs capture metadata about IP traffic, including source/destination IPs, ports, protocols, and action (ACCEPT/REJECT). The ACCEPT action indicates the packet was allowed by both the security group (stateful) and network ACL (stateless). The presence of a public IP (203.0.113.50) in the destination field confirms internet-bound traffic, typically routed via an internet gateway, while the private IP (10.0.2.10) indicates internal VPC communication, likely through a transit gateway or VPC peering.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The instance is communicating with both internal and internet hosts — The VPC Flow Logs show the EC2 instance (10.0.1.5) communicating with both an internal IP (10.0.2.10) on port 443 and an external IP (203.0.113.50) on port 80, with ACCEPT records for both flows. This indicates successful bidirectional traffic to both internal and internet hosts, confirming option D is correct.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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