The answer is two private virtual interfaces, one on each Direct Connect connection. This is correct because active-active failover requires both connections to be simultaneously active, which is achieved by establishing a BGP session over a private VIF on each connection and using AS_PATH prepending to influence traffic flow for load balancing. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this concept tests your understanding of how to design resilient hybrid networking, often appearing in scenario-based questions where you must distinguish between active-active and active-passive configurations. A common trap is assuming a single VIF can provide redundancy or that transit VIFs are needed for VPC connectivity, but transit VIFs only connect to a Direct Connect Gateway, not directly to a VPC. Memory tip: think “two connections, two VIFs, two BGP sessions” for active-active—one VIF per connection is the minimum to keep both paths live.
ANS-C01 Network Implementation Practice Question
This ANS-C01 practice question tests your understanding of network implementation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A company has a Direct Connect connection with a private virtual interface (VIF) to a VPC. They want to add a second Direct Connect connection for redundancy. What is the MINIMUM number of virtual interfaces required to achieve active-active failover for the VPC?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Two private virtual interfaces (one on each connection)
Option B is correct because with two Direct Connect connections, you can create a private VIF on each, and using BGP and AS_PATH prepending, you can achieve active-active load balancing and failover. Option A is wrong because a single VIF cannot provide redundancy. Option C is wrong because you need two VIFs for active-active. Option D is wrong because transit VIFs are for connecting to Direct Connect Gateway, not directly to a VPC.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Two transit virtual interfaces (one on each connection)
Why it's wrong here
Incorrect; transit VIFs connect to Direct Connect Gateway, not directly to VPC.
✗
One private virtual interface and one transit virtual interface
Why it's wrong here
Incorrect; transit VIF is for Direct Connect Gateway, not directly for VPC.
✓
Two private virtual interfaces (one on each connection)
Why this is correct
Correct; two VIFs allow BGP to provide active-active failover.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
One private virtual interface
Why it's wrong here
Incorrect; one VIF is a single point of failure.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related ANS-C01 NAT questions on configuration and troubleshooting.
Network Implementation — This question tests Network Implementation — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Two private virtual interfaces (one on each connection) — Option B is correct because with two Direct Connect connections, you can create a private VIF on each, and using BGP and AS_PATH prepending, you can achieve active-active load balancing and failover. Option A is wrong because a single VIF cannot provide redundancy. Option C is wrong because you need two VIFs for active-active. Option D is wrong because transit VIFs are for connecting to Direct Connect Gateway, not directly to a VPC.
What should I do if I get this ANS-C01 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related ANS-C01 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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