- A
A
Deploy an ExpressRoute circuit for each data center as the primary connection, and a site-to-site VPN as the backup connection for each. This provides high bandwidth and reliability with a cost-effective failover.
- B
B
Why wrong: Using site-to-site VPNs as primary connections may not provide the required high bandwidth and reliability. ExpressRoute circuits as backup would be expensive and not commonly used as a backup due to cost.
- C
C
Why wrong: A single Azure VPN Gateway with active-passive configuration is not designed for primary connections from two data centers; it also does not provide the low latency or reliability of ExpressRoute.
- D
D
Why wrong: Sharing a single ExpressRoute circuit and a single VPN connection between two data centers is not practical as each data center needs its own connection to Azure.
Quick Answer
The answer is Azure ExpressRoute paired with a Site-to-Site VPN gateway. This combination is correct because ExpressRoute delivers the required private, high-bandwidth, and reliable connection for hybrid connectivity, while a VPN gateway provides a low-cost backup path over the internet, avoiding the expense of a second ExpressRoute circuit. On the AZ-305 exam, this scenario tests your understanding of designing cost-effective hybrid networking, where the key trap is assuming redundancy requires a second ExpressRoute circuit—when in fact, a VPN backup meets the requirement at a fraction of the cost. For memory, think of it as “ExpressRoute for the highway, VPN for the dirt road”: the primary route is fast and private, but the backup is cheap and still secure. This directly supports the concept of ExpressRoute with VPN backup for cost-effective hybrid connectivity, a pattern frequently validated in enterprise architecture designs.
AZ-305 Design infrastructure solutions Practice Question
This AZ-305 practice question tests your understanding of design infrastructure solutions. 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 two on-premises data centers and an Azure subscription. They need to connect each data center to Azure with a private, high-bandwidth, and reliable connection. They also want a low-cost backup connection for each data center in case the primary connection fails. Which combination of connectivity options should they recommend?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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
A
Azure ExpressRoute provides a private, high-bandwidth, and reliable connection from on-premises data centers to Azure, bypassing the public internet. To meet the low-cost backup requirement, Azure VPN Gateway (Site-to-Site VPN) offers a secure, encrypted connection over the internet as a failover path, which is significantly cheaper than a second ExpressRoute circuit. This combination ensures primary connectivity via ExpressRoute and cost-effective redundancy via VPN.
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.
- ✓
A
Why this is correct
Deploy an ExpressRoute circuit for each data center as the primary connection, and a site-to-site VPN as the backup connection for each. This provides high bandwidth and reliability with a cost-effective failover.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
B
Why it's wrong here
Using site-to-site VPNs as primary connections may not provide the required high bandwidth and reliability. ExpressRoute circuits as backup would be expensive and not commonly used as a backup due to cost.
- ✗
C
- ✗
D
Why it's wrong here
Sharing a single ExpressRoute circuit and a single VPN connection between two data centers is not practical as each data center needs its own connection to Azure.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume two ExpressRoute circuits are needed for redundancy, overlooking the cost-effective VPN backup option that still meets the 'low-cost' requirement while providing private connectivity only for the primary link.
Detailed technical explanation
How to think about this question
ExpressRoute uses BGP for dynamic routing and offers SLA-backed 99.95% availability, while VPN Gateway uses IPsec/IKE for encryption and can be configured in active-passive mode to failover automatically. In a real-world scenario, the VPN backup can be set up with a lower bandwidth SKU (e.g., VpnGw1) to minimize cost, and route propagation via BGP ensures traffic shifts seamlessly when the ExpressRoute circuit goes down.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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.
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Design infrastructure solutions — study guide chapter
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Design infrastructure solutions practice questions
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FAQ
Questions learners often ask
What does this AZ-305 question test?
Design infrastructure solutions — This question tests Design infrastructure solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A — Azure ExpressRoute provides a private, high-bandwidth, and reliable connection from on-premises data centers to Azure, bypassing the public internet. To meet the low-cost backup requirement, Azure VPN Gateway (Site-to-Site VPN) offers a secure, encrypted connection over the internet as a failover path, which is significantly cheaper than a second ExpressRoute circuit. This combination ensures primary connectivity via ExpressRoute and cost-effective redundancy via VPN.
What should I do if I get this AZ-305 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on AZ-305
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company has an on-premises data center and wants to connect it to Azure to extend their network. They require a dedicated, private, high-bandwidth connection that is not routed over the public internet. They also want a lower-cost backup connection for redundancy in case the primary connection fails. Which combination of connectivity options should they implement?
easy- ✓ A.ExpressRoute as the primary connection and a Site-to-Site VPN as the backup connection.
- B.Two ExpressRoute circuits from different service providers, both active.
- C.Site-to-Site VPN as the primary connection and Point-to-Site VPN as the backup.
- D.Azure VPN Gateway with active-passive mode and a second VPN Gateway for failover.
Why A: ExpressRoute provides a dedicated, private, high-bandwidth connection that bypasses the public internet, meeting the primary requirement. A Site-to-Site VPN over the internet serves as a cost-effective backup path for redundancy, as it uses encrypted tunnels over the public internet without the recurring costs of a second ExpressRoute circuit.
Last reviewed: Jun 11, 2026
This AZ-305 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-305 exam.
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