Quick Answer
The answer is Site-to-Site VPN and ExpressRoute with MACsec. These are the two valid methods to secure traffic between on-premises and Azure because each provides encryption for data in transit, though at different layers of the OSI model. A Site-to-Site VPN uses IPsec (IKEv1 or IKEv2) to create an encrypted tunnel over the public internet between your on-premises VPN device and Azure VPN Gateway, while ExpressRoute with MACsec applies the IEEE 802.1AE standard to encrypt traffic at Layer 2 over a private, dedicated connection that never touches the public internet. On the Microsoft Cybersecurity Architect exam, this question tests your understanding of securing hybrid connectivity and often appears as a trap where candidates mistakenly select only one option or confuse MACsec with basic ExpressRoute, which alone does not encrypt traffic. A helpful memory tip is to think “VPN for internet, MACsec for private line”—both encrypt, but one rides the public cloud and the other rides a private circuit.
This SC-100 practice question tests your understanding of design security for infrastructure. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
Which TWO of the following are valid methods to secure traffic between on-premises and Azure?
Azure Front Door
Why wrong: Front Door is for web applications, not site-to-site.
ExpressRoute with MACsec
MACsec provides encryption on ExpressRoute.
Azure Traffic Manager
Why wrong: Traffic Manager is for DNS routing.
Azure CDN
Why wrong: CDN is for content delivery.
Site-to-Site VPN
VPN provides encrypted connection over the internet.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ExpressRoute with MACsec
ExpressRoute with MACsec provides encryption at Layer 2 using the IEEE 802.1AE standard, securing traffic between on-premises and Azure over a private connection without traversing the public internet. Site-to-Site VPN uses IPsec (IKEv1/IKEv2) to encrypt traffic over the public internet, establishing a secure tunnel between the on-premises VPN device and Azure VPN Gateway. Both are valid methods for securing traffic, with ExpressRoute+MACsec offering lower latency and higher throughput for private connectivity.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Azure Front Door
Why it's wrong here
Front Door is for web applications, not site-to-site.
ExpressRoute with MACsec
Why this is correct
MACsec provides encryption on ExpressRoute.
Related concept
Read the scenario before looking for a memorised answer.
Azure Traffic Manager
Why it's wrong here
Traffic Manager is for DNS routing.
Azure CDN
Why it's wrong here
CDN is for content delivery.
Site-to-Site VPN
Why this is correct
VPN provides encrypted connection over the internet.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse Azure Front Door or Traffic Manager as security solutions because they offer TLS termination or DDoS protection, but neither provides encrypted site-to-site connectivity between on-premises and Azure; they are traffic routing and acceleration services, not VPN or private connection methods.
Detailed technical explanation
ExpressRoute with MACsec encrypts the Ethernet frames using a GCM-AES-128 or GCM-AES-256 cipher, with the MACsec Key Agreement (MKA) protocol (IEEE 802.1X-2010) managing key exchange between the on-premises router and the Microsoft Enterprise Edge (MSEE) device. Site-to-Site VPN relies on IPsec in tunnel mode, typically using IKEv2 for key exchange and ESP (Encapsulating Security Payload) for encryption, with support for AES-256 and SHA-256. A real-world scenario where this matters is a financial institution that requires both low-latency private connectivity (ExpressRoute) and encryption compliance (MACsec) for regulatory mandates like PCI DSS, while using Site-to-Site VPN as a backup or for branch offices with lower throughput needs.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
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FAQ
Design security for infrastructure — This question tests Design security for infrastructure — Read the scenario before looking for a memorised answer..
The correct answer is: ExpressRoute with MACsec — ExpressRoute with MACsec provides encryption at Layer 2 using the IEEE 802.1AE standard, securing traffic between on-premises and Azure over a private connection without traversing the public internet. Site-to-Site VPN uses IPsec (IKEv1/IKEv2) to encrypt traffic over the public internet, establishing a secure tunnel between the on-premises VPN device and Azure VPN Gateway. Both are valid methods for securing traffic, with ExpressRoute+MACsec offering lower latency and higher throughput for private connectivity.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This SC-100 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 SC-100 exam.
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