The answer is to use a global external HTTP(S) load balancer and add both MIGs as backends. This works because a global HTTP(S) load balancer operates at a single anycast IP address, allowing it to intelligently route traffic from each client to the closest healthy backend based on geographic location and backend health probes, without requiring DNS-based failover or redirects. On the Google Professional Cloud Architect exam, this scenario tests your understanding of global versus regional load balancing, often appearing in multi-region high-availability questions where a common trap is choosing a regional load balancer or adding a separate DNS step. Remember that the global HTTP(S) load balancer inherently handles proximity-based routing across regions, so you simply add both instance groups as backends to the same forwarding rule. A helpful memory tip: think of the global load balancer as a single front door that automatically points each visitor to the nearest open register.
Google PCA Manage implementation of cloud architecture Practice Question
This PCA practice question tests your understanding of manage implementation of cloud architecture. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 is using Cloud Load Balancing to distribute traffic to a managed instance group (MIG) of web servers. The web servers are currently running in us-central1. To improve availability, the company plans to add a second MIG in us-west1. What must be done to ensure traffic is automatically routed to the closest healthy backend?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a global external HTTP(S) load balancer and add both MIGs as backends.
A global external HTTP(S) load balancer can route traffic to backends in multiple regions and automatically directs requests to the closest healthy backend based on the client's geographic location and backend health. Adding both MIGs as backends to this single anycast IP ensures traffic is distributed to the nearest region without additional DNS-based routing or redirects.
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.
✗
Use a Network Load Balancer in us-central1 and configure a redirect to the new MIG.
Why it's wrong here
Network Load Balancer is regional and cannot redirect to another region; it would need multiple load balancers.
✓
Use a global external HTTP(S) load balancer and add both MIGs as backends.
Why this is correct
Global HTTP(S) load balancer provides cross-region load balancing with intelligent routing.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use an internal TCP/UDP load balancer in each region and configure DNS-based routing.
Why it's wrong here
Internal load balancers are for internal traffic and not suitable for internet-facing applications.
✗
Use an external TCP/UDP Network Load Balancer with the new MIG as an additional backend.
Why it's wrong here
Network Load Balancers are regional and cannot route across regions.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse regional load balancers (Network Load Balancer, TCP/UDP Proxy) with global load balancers, assuming any external load balancer can span regions, but only the global external HTTP(S) load balancer (and the global external SSL proxy) support multi-region backends with automatic proximity-based routing.
Detailed technical explanation
How to think about this question
The global external HTTP(S) load balancer uses Google Front End (GFE) anycast IPs and a global forwarding rule to terminate traffic at the edge, then proxies requests to the closest healthy backend based on the client's source IP and the load balancing scheme. It supports cross-regional backend services with automatic failover: if the nearest backend is unhealthy, traffic is routed to the next closest healthy backend. This differs from DNS-based approaches (e.g., geo-routing) which rely on client-side caching and can cause slower failover.
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
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this PCA question in full detail.
Manage implementation of cloud architecture — This question tests Manage implementation of cloud architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use a global external HTTP(S) load balancer and add both MIGs as backends. — A global external HTTP(S) load balancer can route traffic to backends in multiple regions and automatically directs requests to the closest healthy backend based on the client's geographic location and backend health. Adding both MIGs as backends to this single anycast IP ensures traffic is distributed to the nearest region without additional DNS-based routing or redirects.
What should I do if I get this PCA 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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